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<A HREF="toc.html">Contents</A>
<A HREF="policygroups.html">Previous</A>
<A HREF="manpages.html">Next</A>
<HR>
<H1><A NAME="5">FreeS/WAN FAQ</A></H1>
<P>This is a collection of questions and answers, mostly taken from the
 FreeS/WAN<A href="mail.html"> mailing list</A>. See the project<A href="http://www.freeswan.org/">
 web site</A> for more information. All the FreeS/WAN documentation is
 online there.</P>
<P>Contributions to the FAQ are welcome. Please send them to the project<A
href="mail.html"> mailing list</A>.</P>
<HR>
<H2><A name="questions">Index of FAQ questions</A></H2>
<UL>
<LI><A href="#whatzit">What is FreeS/WAN?</A></LI>
<LI><A href="#problems">How do I report a problem or seek help?</A></LI>
<LI><A href="#generic">Can I get ...</A>
<UL>
<LI><A href="#lemme_out">... an off-the-shelf system that includes
 FreeS/WAN?</A></LI>
<LI><A href="#contractor">... contractors or staff who know FreeS/WAN?</A>
</LI>
<LI><A href="#commercial">... commercial support?</A></LI>
</UL>
</LI>
<LI><A href="#release">Release questions</A>
<UL>
<LI><A href="#rel.current">What is the current release?</A></LI>
<LI><A href="#relwhen">When is the next release?</A></LI>
<LI><A href="#rel.bugs">Are there known bugs in the current release?</A></LI>
</UL>
</LI>
<LI><A href="mod_cons">Modifications and contributions</A>
<UL>
<LI><A href="#modify.faq">Can I modify FreeS/WAN to ...?</A></LI>
<LI><A href="#contrib.faq">Can I contribute to the project?</A></LI>
<LI><A href="#ddoc.faq">Is there detailed design documentation?</A></LI>
</UL>
</LI>
<LI><A href="#interact">Will FreeS/WAN work in my environment?</A>
<UL>
<LI><A href="#interop.faq">Can FreeS/WAN talk to ... ?</A></LI>
<LI><A href="#old_to_new">Can different FreeS/WAN versions talk to each
 other?</A></LI>
<LI><A href="#faq.bandwidth">Is there a limit on throughput?</A></LI>
<LI><A href="#faq.number">Is there a limit on number of connections?</A></LI>
<LI><A href="#faq.speed">Is a ... fast enough to handle FreeS/WAN with
 my loads?</A></LI>
</UL>
</LI>
<LI><A href="#work_on">Will FreeS/WAN work on ...</A>
<UL>
<LI><A href="#versions">... my version of Linux?</A></LI>
<LI><A href="#nonIntel.faq">... non-Intel CPUs?</A></LI>
<LI><A href="#multi.faq">... multiprocessors?</A></LI>
<LI><A href="#k.old">... an older kernel?</A></LI>
<LI><A href="#k.versions">... the latest kernel version?</A></LI>
<LI><A href="#interface.faq">... unusual network hardware?</A></LI>
<LI><A href="#vlan">... a VLAN (802.1q) network?</A></LI>
</UL>
</LI>
<LI><A href="#features.faq">Does FreeS/WAN support ...</A>
<UL>
<LI><A href="#VPN.faq">... site-to-site VPN applications</A></LI>
<LI><A href="#warrior.faq">... remote users connecting to a LAN</A></LI>
<LI><A href="#road.shared.possible">... remote users using shared secret
 authentication?</A></LI>
<LI><A href="#wireless.faq">... wireless networks</A></LI>
<LI><A href="#PKIcert">... X.509 or other PKI certificates?</A></LI>
<LI><A href="#Radius">... user authentication (Radius, SecureID, Smart
 Card ...)?</A></LI>
<LI><A href="#NATtraversal">... NAT traversal</A></LI>
<LI><A href="#virtID">... assigning a &quot;virtual identity&quot; to a remote
 system?</A></LI>
<LI><A href="#noDES.faq">... single DES encryption?</A></LI>
<LI><A href="#AES.faq">... AES encryption?</A></LI>
<LI><A href="#other.cipher">... other encryption algorithms?</A></LI>
</UL>
</LI>
<LI><A href="#canI">Can I ...</A>
<UL>
<LI><A href="#policy.preconfig">...use policy groups along with
 explicitly configured connections?</A></LI>
<LI><A href="#policy.off">...turn off policy groups?</A></LI>

<!--
      <li><a href="#policy.otherinterface">...use policy groups
      on an interface other than <VAR>%defaultroute</VAR>?</a></li>
-->
<LI><A href="#reload">... reload connection info without restarting?</A></LI>
<LI><A href="#masq.faq">... use several masqueraded subnets?</A></LI>
<LI><A href="#dup_route">... use subnets masqueraded to the same
 addresses?</A></LI>
<LI><A href="#road.masq">... assign a road warrior an address on my net
 (a virtual identity)?</A></LI>
<LI><A href="#road.many">... support many road warriors with one
 gateway?</A></LI>
<LI><A href="#road.PSK">... have many road warriors using shared secret
 authentication?</A></LI>
<LI><A href="#QoS">... use Quality of Service routing with FreeS/WAN?</A>
</LI>
<LI><A href="#deadtunnel">... recognise dead tunnels and shut them down?</A>
</LI>
<LI><A href="#demanddial">... build IPsec tunnels over a demand-dialed
 link?</A></LI>
<LI><A href="#GRE">... build GRE, L2TP or PPTP tunnels over IPsec?</A></LI>
<LI><A href="#NetBIOS">... use Network Neighborhood (Samba, NetBIOS)
 over IPsec?</A></LI>
</UL>
</LI>
<LI><A href="#setup.faq">Life's little mysteries</A>
<UL>
<LI><A href="#cantping">I cannot ping ....</A></LI>
<LI><A href="#forever">It takes forever to ...</A></LI>
<LI><A href="#route">I send packets to the tunnel with route(8) but they
 vanish</A></LI>
<LI><A href="#down_route">When a tunnel goes down, packets vanish</A></LI>
<LI><A href="#firewall_ate">The firewall ate my packets!</A></LI>
<LI><A href="#dropconn">Dropped connections</A></LI>
<LI><A href="#defaultroutegone">Disappearing %defaultroute</A></LI>
<LI><A href="#tcpdump.faq">TCPdump on the gateway shows strange things</A>
</LI>
<LI><A href="#no_trace">Traceroute does not show anything between the
 gateways</A></LI>
</UL>
</LI>
<LI><A href="#man4debug">Testing in stages (or .... works but ...
 doesn't)</A>
<UL>
<LI><A href="#nomanual">Manually keyed connections don't work</A></LI>
<LI><A href="#spi_error">One manual connection works, but second one
 fails</A></LI>
<LI><A href="#man_no_auto">Manual connections work, but automatic keying
 doesn't</A></LI>
<LI><A href="#nocomp">IPsec works, but connections using compression
 fail</A></LI>
<LI><A href="#pmtu.broken">Small packets work, but large transfers fail</A>
</LI>
<LI><A href="#subsub">Subnet-to-subnet works, but tests from the
 gateways don't</A></LI>
</UL>
</LI>
<LI><A href="#compile.faq">Compilation problems</A>
<UL>
<LI><A href="#gmp.h_missing">gmp.h: No such file or directory</A></LI>
<LI><A href="#noVM">... virtual memory exhausted</A></LI>
</UL>
</LI>
<LI><A href="#error">Interpreting error messages</A>
<UL>
<LI><A href="#route-client">route-client (or host) exited with status 7</A>
</LI>
<LI><A href="#unreachable">SIOCADDRT:Network is unreachable</A></LI>
<LI><A href="#modprobe">ipsec_setup: modprobe: Can't locate moduleipsec</A>
</LI>
<LI><A href="#noKLIPS">ipsec_setup: Fatal error, kernel appears to lack
 KLIPS</A></LI>
<LI><A href="#noDNS">ipsec_setup: ... failure to fetch key for ... from
 DNS</A></LI>
<LI><A href="#dup_address">ipsec_setup: ... interfaces ... and ... share
 address ...</A></LI>
<LI><A href="#kflags">ipsec_setup: Cannot adjust kernel flags</A></LI>
<LI><A href="#message_num">Message numbers (MI3, QR1, et cetera) in
 Pluto messages</A></LI>
<LI><A href="#conn_name">Connection names in Pluto error messages</A></LI>
<LI><A href="#cantorient">Pluto: ... can't orient connection</A></LI>
<LI><A href="#no.interface">... we have no ipsecN interface for either
 end of this connection</A></LI>
<LI><A href="#noconn">Pluto: ... no connection is known</A></LI>
<LI><A href="#nosuit">Pluto: ... no suitable connection ...</A></LI>
<LI><A href="#noconn.auth">Pluto: ... no connection has been authorized</A>
</LI>
<LI><A href="#noDESsupport">Pluto: ... OAKLEY_DES_CBC is not supported.</A>
</LI>
<LI><A href="#notransform">Pluto: ... no acceptable transform</A></LI>
<LI><A href="#rsasigkey">rsasigkey dumps core</A></LI>
<LI><A href="#sig4">!Pluto failure!: ... exited with ... signal 4</A></LI>
<LI><A href="#econnrefused">ECONNREFUSED error message</A></LI>
<LI><A href="#no_eroute">klips_debug: ... no eroute!</A></LI>
<LI><A href="#SAused">... trouble writing to /dev/ipsec ... SA already
 in use</A></LI>
<LI><A href="#ignore">... ignoring ... payload</A></LI>
<LI><A href="#unknown_rightcert">unknown parameter name &quot;rightcert&quot;</A></LI>
</UL>
</LI>
<LI><A href="#spam">Why don't you restrict the mailing lists to reduce
 spam?</A></LI>
</UL>
<HR>
<H2><A name="whatzit">What is FreeS/WAN?</A></H2>
<P>FreeS/WAN is a Linux implementation of the<A href="glossary.html#IPSEC">
 IPsec</A> protocols, providing security services at the IP (Internet
 Protocol) level of the network.</P>
<P>For more detail, see our<A href="intro.html"> introduction</A>
 document or the FreeS/WAN project<A href="http://www.freeswan.org/">
 web site</A>.</P>
<P>To start setting it up, go to our<A href="quickstart.html">
 quickstart guide</A>.</P>
<P>Our<A href="web.html"> web links</A> document has information on<A href="web.html#implement">
 IPsec for other systems</A>.</P>
<H2><A name="problems">How do I report a problem or seek help?</A></H2>
<DL>
<DT>Read our<A href="trouble.html"> troubleshooting</A> document.</DT>
<DD>
<P>It may guide you to a solution. If not, see its<A href="trouble.html#prob.report">
 problem reporting</A> section.</P>
<P>Basically, what it says is<STRONG> give us the output from<VAR> ipsec
 barf</VAR> from both gateways</STRONG>. Without full information, we
 cannot diagnose a problem. However,<VAR> ipsec barf</VAR> produces a
 lot of output. If at all possible,<STRONG> please make barfs accessible
 via the web or FTP</STRONG> rather than sending enormous mail messages.</P>
</DD>
<DT><STRONG>Use the<A href="mail.html"> users mailing list</A> for
 problem reports</STRONG>, rather than mailing developers directly.</DT>
<DD>
<UL>
<LI>This gives you access to more expertise, including users who may
 have encountered and solved the same problems.</LI>
<LI>It is more likely to get a quick response. Developers may get behind
 on email, or even ignore it entirely for a while, but a list message
 (given a reasonable Subject: line) is certain to be read by a fair
 number of people within hours.</LI>
<LI>It may also be important because of<A href="politics.html#exlaw">
 cryptography export laws</A>. A US citizen who provides technical
 assistance to foreign cryptographic work might be charged under the
 arms export regulations. Such a charge would be easier to defend if the
 discussion took place on a public mailing list than if it were done in
 private mail.</LI>
</UL>
</DD>
<DT>Try irc.freenode.net#freeswan.</DT>
<DD>
<P>FreeS/WAN developers, volunteers and users can often be found there.
 Be patient and be prepared to provide lots of information to support
 your question.</P>
<P>If your question was really interesting, and you found an answer,
 please share that with the class by posting to the<A href="mail.html">
 users mailing list</A>. That way others with the same problem can find
 your answer in the archives.</P>
</DD>
<DT>Premium support is also available.</DT>
<DD>
<P>See the next several questions.</P>
</DD>
</DL>
<H2><A name="generic">Can I get ...</A></H2>
<H3><A name="lemme_out">Can I get an off-the-shelf system that includes
 FreeS/WAN?</A></H3>
<P>There are a number of Linux distributions or firewall products which
 include FreeS/WAN. See this<A href="intro.html#products"> list</A>.
 Using one of these, chosen to match your requirements and budget, may
 save you considerable time and effort.</P>
<P>If you don't know your requirements, start by reading Schneier's<A href="biblio.html#secrets">
 Secrets and Lies</A>. That gives the best overview of security issues I
 have seen. Then consider hiring a consultant (see next question) to
 help define your requirements.</P>
<H3><A name="consultant">Can I hire consultants or staff who know
 FreeS/WAN?</A></H3>
<P>If you want the help of a contractor, or to hire staff with FreeS/WAN
 expertise, you could:</P>
<UL>
<LI>check availability in your area through your local Linux User Group
 (<A href="http://lugww.counter.li.org/">LUG Index</A>)</LI>
<LI>try asking on our<A href="mail.html"> mailing list</A></LI>
</UL>
<P>For companies offerring support, see the next question.</P>
<H3><A name="commercial">Can I get commercial support?</A></H3>
<P>Many of the distributions or firewall products which include
 FreeS/WAN (see this<A href="intro.html#products"> list</A>) come with
 commercial support or have it available as an option.</P>
<P>Various companies specialize in commercial support of open source
 software. Our project leader was a founder of the first such company,
 Cygnus Support. It has since been bought by<A href="http://www.redhat.com">
 Redhat</A>. Another such firm is<A href="http://www.linuxcare.com">
 Linuxcare</A>.</P>
<H2><A name="release">Release questions</A></H2>
<H3><A name="rel.current">What is the current release?</A></H3>
<P>The current release is the highest-numbered tarball on our<A href="ftp://ftp.xs4all.nl/pub/crypto/freeswan">
 distribution site</A>. Almost always, any of<A href="intro.html#mirrors">
 the mirrors</A> will have the same file, though perhaps not for a day
 or so after a release.</P>
<P>Unfortunately, the web site is not always updated as quickly as it
 should be.</P>
<H3><A name="relwhen">When is the next release?</A></H3>
<P>We try to do a release approximately every six to eight weeks.</P>
<P>If pre-release tests fail and the fix appears complex, or more
 generally if the code does not appear stable when a release is
 scheduled, we will just skip that release.</P>
<P>For serious bugs, we may bring out an extra bug-fix release. These
 get numbers in the normal release series. For example, there was a bug
 found in FreeS/WAN 1.6, so we did another release less than two weeks
 later. The bug-fix release was called 1.7.</P>
<H3><A name="rel.bugs">Are there known bugs in the current release?</A></H3>
<P>Any problems we are aware of at the time of a release are documented
 in the<A href="../BUGS"> BUGS</A> file for that release. You should
 also look at the<A href="../CHANGES"> CHANGES</A> file.</P>
<P>Bugs discovered after a release are discussed on the<A href="mail.html">
 mailing lists</A>. The easiest way to check for any problems in the
 current code would be to peruse the<A href="http://lists.freeswan.org/pipermail/briefs">
 List In Brief</A>.</P>
<H2><A name="mod_cons">Modifications and contributions</A></H2>
<H3><A name="modify.faq">Can I modify FreeS/WAN to ...?</A></H3>
<P>You are free to modify FreeS/WAN in any way. See the discussion of<A href="intro.html#licensing">
 licensing</A> in our introduction document.</P>
<P>Before investing much energy in any such project, we suggest that you</P>
<UL>
<LI>check the list of<A href="web.html#patch"> existing patches</A></LI>
<LI>post something about your project to the<A href="mail.html"> design
 mailing list</A></LI>
</UL>
<P>This may prevent duplicated effort, or lead to interesting
 collaborations.</P>
<H3><A name="contrib.faq">Can I contribute to the project?</A></H3>
 In general, we welcome contributions from the community. Various
 contributed patches, either to fix bugs or to add features, have been
 incorporated into our distribution. Other patches, not yet included in
 the distribution, are listed in our<A href="web.html#patch"> web links</A>
 section.
<P>Users have also contributed heavily to documentation, both by
 creating their own<A href="intro.html#howto"> HowTos</A> and by posting
 things on the<A href="mail.html"> mailing lists</A> which I have quoted
 in these HTML docs.</P>
<P>There are, however, some caveats.</P>
<P>FreeS/WAN is being implemented in Canada, by Canadians, largely to
 ensure that is it is entirely free of export restrictions. See this<A href="politics.html#status">
 discussion</A>. We<STRONG> cannot accept code contributions from US
 residents or citizens</STRONG>, not even one-line bugs fixes. The
 reasons for this were recently discussed extensively on the mailing
 list, in a thread starting<A href="http://www.sandelman.ottawa.on.ca/linux-ipsec/html/2001/01/msg00111.html">
 here</A>.</P>
<P>Not all contributions are of interest to us. The project has a set of
 fairly ambitious and quite specific goals, described in our<A href="intro.html#goals">
 introduction</A>. Contributions that lead toward these goals are likely
 to be welcomed enthusiastically. Other contributions may be seen as
 lower priority, or even as a distraction.</P>
<P>Discussion of possible contributions takes place on the<A href="mail.html">
 design mailing list</A>.</P>
<H3><A name="ddoc.faq">Is there detailed design documentation?</A></H3>
 There are:
<UL>
<LI><A href="rfc.html">RFCs</A> specifying the protocols we implement</LI>
<LI><A href="manpages.html">man pages</A> for our utilities, library
 functions and file formats</LI>
<LI>comments in the source code</LI>
<LI><A href="index.html">HTML documentation</A> written primarily for
 users</LI>
<LI>archived discussions from the<A href="mail.html"> mailing lists</A></LI>
<LI>other papers mentioned in our<A href="intro.html#applied">
 introduction</A></LI>
</UL>
<P>The only formal design documents are a few papers in the last
 category above. All the other categories, however, have things to say
 about design as well.</P>
<H2><A name="interact">Will FreeS/WAN work in my environment?</A></H2>
<H3><A name="interop.faq">Can FreeS/WAN talk to ...?</A></H3>
<P>The IPsec protocols are designed to support interoperation. In
 theory, any two IPsec implementations should be able to talk to each
 other. In practice, it is considerably more complex. We have a whole<A href="interop.html">
 interoperation document</A> devoted to this problem.</P>
<P>An important part of that document is links to the many<A href="interop.html#otherpub">
 user-written HowTos</A> on interoperation between FreeS/WAN and various
 other implementations. Often the users know more than the developers
 about these issues (and almost always more than me :-), so these
 documents may be your best resource.</P>
<H3><A name="old_to_new">Can different FreeS/WAN versions talk to each
 other?</A></H3>
<P>Linux FreeS/WAN can interoperate with many IPsec implementations,
 including earlier versions of Linux FreeS/WAN itself.</P>
<P>In a few cases, there are some complications. See our<A href="interop.html#oldswan">
 interoperation</A> document for details.</P>
<H3><A name="faq.bandwidth">Is there a limit on throughput?</A></H3>
<P>There is no hard limit, but see below.</P>
<H3><A name="faq.number">Is there a limit on number of tunnels?</A></H3>
<P>There is no hard limit, but see next question.</P>
<H3><A name="faq.speed">Is a ... fast enough to handle FreeS/WAN with my
 loads?</A></H3>
<P>A quick summary:</P>
<DL>
<DT>Even a limited machine can be useful</DT>
<DD>A 486 can handle a T1, ADSL or cable link, though the machine may be
 breathing hard.</DD>
<DT>A mid-range PC (say 800 MHz with good network cards) can do a lot of
 IPsec</DT>
<DD>With up to roughly 50 tunnels and aggregate bandwidth of 20 Megabits
 per second, it willl have cycles left over for other tasks.</DD>
<DT>There are limits</DT>
<DD>Even a high end CPU will not come close to handling a fully loaded
 100 Mbit/second Ethernet link.
<P>Beyond about 50 tunnels it needs careful management.</P>
</DD>
</DL>
<P>See our<A href="performance.html"> FreeS/WAN performance</A> document
 for details.</P>
<H2><A name="work_on">Will FreeS/WAN work on ... ?</A></H2>
<H3><A name="versions">Will FreeS/WAN run on my version of Linux?</A></H3>
<P>We build and test on Redhat distributions, but FreeS/WAN runs just
 fine on several other distributions, sometimes with minor fiddles to
 adapt to the local environment. Details are in our<A href="compat.html#otherdist">
 compatibility</A> document. Also, some distributions or products come
 with<A href="intro.html#products"> FreeS/WAN included</A>.</P>
<H3><A name="nonIntel.faq">Will FreeS/WAN run on non-Intel CPUs?</A></H3>
<P>FreeS/WAN is<STRONG> intended to run on all CPUs Linux supports</STRONG>
. We know of it being used in production on x86, ARM, Alpha and MIPS. It
 has also had successful tests on PPC and SPARC, though we don't know of
 actual use there. Details are in our<A href="compat.html#CPUs">
 compatibility</A> document.</P>
<H3><A name="multi.faq">Will FreeS/WAN run on multiprocessors?</A></H3>
<P>FreeS/WAN is designed to work on any SMP architecture Linux supports,
 and has been tested successfully on at least dual processor Intel
 architecture machines. Details are in our<A href="compat.html#multiprocessor">
 compatibility</A> document.</P>
<H3><A name="k.old">Will FreeS/WAN work on an older kernel?</A></H3>
<P>It might, but we strongly recommend using a recent 2.2 or 2.4 series
 kernel. Sometimes the newer versions include security fixes which can
 be quite important on a gateway.</P>
<P>Also, we use recent kernels for development and testing, so those are
 better tested and, if you do encounter a problem, more easily
 supported. If something breaks applying recent FreeS/WAN patches to an
 older kernel, then &quot;update your kernel&quot; is almost certain to be the
 first thing we suggest. It may be the only suggestion we have.</P>
<P>The precise kernel versions supported by a particular FreeS/WAN
 release are given in the<A href="XX"> README</A> file of that release.</P>
<P>See the following question for more on kernels.</P>
<H3><A name="k.versions">Will FreeS/WAN run on the latest kernel
 version?</A></H3>
<P>Sometimes yes, but quite often, no.</P>
<P>Kernel versions supported are given in the<A href="../README"> README</A>
 file of each FreeS/WAN release. Typically, they are whatever production
 kernels were current at the time of our release (or shortly before; we
 might release for kernel<VAR> n</VAR> just as Linus releases<VAR> n+1</VAR>
). Often FreeS/WAN will work on slightly later kernels as well, but of
 course this cannot be guaranteed.</P>
<P>For example, FreeS/WAN 1.91 was released for kernels 2.2.19 or 2.4.5,
 the current kernels at the time. It also worked on 2.4.6, 2.4.7 and
 2.4.8, but 2.4.9 had changes that caused compilation errors if it was
 patched with FreeS/WAN 1.91.</P>
<P>When such changes appear, we put a fix in the FreeS/WAN snapshots,
 and distribute it with our next release. However, this is not a high
 priority for us, and it may take anything from a few days to several
 weeks for such a problem to find its way to the top of our kernel
 programmer's To-Do list. In the meanwhile, you have two choices:</P>
<UL>
<LI>either stick with a slightly older kernel, even if it is not the
 latest and greatest. This is recommended for production systems; new
 versions may have new bugs.</LI>
<LI>or fix the problem yourself and send us a patch, via the<A href="mail.html">
 Users mailing list</A>.</LI>
</UL>
<P>We don't even try to keep up with kernel changes outside the main 2.2
 and 2.4 branches, such as the 2.4.x-ac patched versions from Alan Cox
 or the 2.5 series of development kernels. We'd rather work on
 developing the FreeS/WAN code than on chasing these moving targets. We
 are, however, happy to get patches for problems discovered there.</P>
<P>See also the<A href="install.html#choosek"> Choosing a kernel</A>
 section of our installation document.</P>
<H3><A name="interface.faq">Will FreeS/WAN work on unusual network
 hardware?</A></H3>
<P>IPsec is designed to work over any network that IP works over, and
 FreeS/WAN is intended to work over any network interface hardware that
 Linux supports.</P>
<P>If you have working IP on some unusual interface -- perhaps Arcnet,
 Token Ring, ATM or Gigabit Ethernet -- then IPsec should &quot;just work&quot;.</P>
<P>That said, practice is sometimes less tractable than theory. Our
 testing is done almost entirely on:</P>
<UL>
<LI>10 or 100 Mbit Ethernet</LI>
<LI>ADSL or cable connections, with and without PPPoE</LI>
<LI>IEEE 802.11 wireless LANs (see<A href="#wireless.faq"> below</A>)</LI>
</UL>
<P>If you have some other interface, especially an uncommon one, it is
 entirely possible you will get bitten either by a FreeS/WAN bug which
 our testing did not turn up, or by a bug in the driver that shows up
 only with our loads.</P>
<P>If IP works on your interface and FreeS/WAN doesn't, seek help on the<A
href="mail.html"> mailing lists</A>.</P>
<P>Another FAQ section describes<A href="#pmtu.broken"> MTU problems</A>
. These are a possibility for some interfaces.</P>
<H3><A name="vlan">Will FreeS/WAN work on a VLAN (802.1q) network?</A></H3>
<P> Yes, FreeSwan works fine, though some network drivers have problems
 with jumbo sized ethernet frames. If you used interfaces=%defaultroute
 you do not need to change anything, but if you specified an interface
 (eg eth0) then remember you must change that to reflect the VLAN
 interface (eg eth0.2 for VLAN ID 2).</P>
<P> The &quot;eepro100&quot; module is known to be broken, use the e100 driver for
 those cards instead (included in 2.4 as 'alternative driver' for the
 Intel EtherExpressPro/100.</P>
<P> You do not need to change any MTU setting (those are workarounds
 that are only needed for buggy drivers)</P>
<P><EM>This FAQ contributed by Paul Wouters.</EM></P>
<H2><A name="features.faq">Does FreeS/WAN support ...</A></H2>
<P>For a discussion of which parts of the IPsec specifications FreeS/WAN
 does and does not implement, see our<A href="compat.html#spec">
 compatibility</A> document.</P>
<P>For information on some often-requested features, see below.</P>
<H3><A name="VPN.faq"></A>Does FreeS/WAN support site-to-site VPN (<A HREF="glossary.html#VPN">
Virtual Private Network</A>) applications?</H3>
<P>Absolutely. See this FreeS/WAN-FreeS/WAN<A HREF="config.html">
 configuration example</A>. If only one site is using FreeS/WAN, there
 may be a relevant HOWTO on our<A HREF="interop.html"> interop page</A>.</P>
<H3><A name="warrior.faq">Does FreeS/WAN support remote users connecting
 to a LAN?</A></H3>
<P>Yes. We call the remote users &quot;Road Warriors&quot;. Check out our
 FreeS/WAN-FreeS/WAN<A HREF="config.html#config.rw"> Road Warrior
 Configuration Example</A>.</P>
<P>If your Road Warrior is a Windows or Mac PC, you may need to install
 an IPsec implementation on that machine. Our<A HREF="interop.html">
 interop</A> page lists many available brands, and features links to
 several HOWTOs.</P>
<H3><A name="road.shared.possible">Does FreeS/WAN support remote users
 using shared secret authentication?</A></H3>
<P><STRONG>Yes, but</STRONG> there are severe restrictions, so<STRONG>
 we strongly recommend using</STRONG><A href="glossary.html#RSA"><STRONG>
 RSA</STRONG></A><STRONG> keys for</STRONG><A href="glossary.html#authentication">
<STRONG> authentication</STRONG></A><STRONG> instead</STRONG>.</P>
<P>See this<A href="#road.PSK"> FAQ question</A>.</P>
<H3><A name="wireless.faq">Does FreeS/WAN support wireless networks?</A></H3>
<P>Yes, it is a common practice to use IPsec over wireless networks
 because their built-in encryption,<A href="glossary.html#WEP"> WEP</A>,
 is insecure.</P>
<P>There is some<A href="adv_config.html#wireless.config"> discussion</A>
 in our advanced configuration document. See also the<A HREF="http://www.wavesec.org">
 WaveSEC site</A>.</P>
<H3><A name="PKIcert">Does FreeS/WAN support X.509 or other PKI
 certificates?</A></H3>
<P>Vanilla FreeS/WAN does not support X.509, but Andreas Steffen and
 others have provided a popular, well-supported X.509 patch.</P>
<UL>
<LI><A HREF="http://www.strongsec.com/freeswan">patch</A></LI>
<LI><A HREF="http://www.freeswan.ca">Super FreeS/WAN</A> incorporates
 this and other user-contributed patches.</LI>
<LI> Kai Martius'<A HREF="http://www.strongsec.com/freeswan/install.htm">
 X.509 Installation and Configuration Guide</A></LI>
</UL>
<P> Linux FreeS/WAN features<A HREF="quickstart.html"> Opportunistic
 Encryption</A>, an alternative Public Key Infrastructure based on
 Secure DNS.</P>
<H3><A name="Radius">Does FreeS/WAN support user authentication (Radius,
 SecureID, Smart Card...)?</A></H3>
<P>Andreas Steffen's<A HREF="http://www.strongsec.com/freeswan"> X.509
 patch</A> (v. 1.42+) supports Smart Cards. The patch does not ship with
 vanilla FreeS/WAN, but will be incorporated into<A HREF="http://www.freeswan.ca/">
 Super FreeS/WAN 2.01+</A>. The patch implements the PCKS#15
 Cryptographic Token Information Format Standard, using the OpenSC
 smartcard library functions.</P>
<P>Older news:</P>
<P>A user-supported patch to FreeS/WAN 1.3, for smart card style
 authentication, is available on<A HREF="http://alcatraz.webcriminals.com/~bastiaan/ipsec">
 Bastiaan's site</A>. It supports skeyid and ibutton. This patch is not
 part of Super FreeS/WAN.</P>
<P>For a while progress on this front was impeded by a lack of standard.
 The IETF<A href="http://www.ietf.org/html.charters/ipsra-charter.html">
 working group</A> has now nearly completed its recommended solution to
 the problem; meanwhile several vendors have implemented various things.</P>

<!--
<p>The <a href="web.html#patch">patches</a> section of our web links document
has links to some user work on this.</p>
-->
<P>Of course, there are various ways to avoid any requirement for user
 authentication in IPsec. Consider the situation where road warriors
 build IPsec tunnels to your office net and you are considering
 requiring user authentication during tunnel negotiation. Alternatives
 include:</P>
<UL>
<LI>If you can trust the road warrior machines, then set them up so that
 only authorised users can create tunnels. If your road warriors use
 laptops, consider the possibility of theft.</LI>
<LI>If the tunnel only provides access to particular servers and you can
 trust those servers, then set the servers up to require user
 authentication.</LI>
</UL>
<P>If either of those is trustworthy, it is not clear that you need user
 authentication in IPsec.</P>
<H3><A name="NATtraversal">Does FreeS/WAN support NAT traversal?</A></H3>
<P>Vanilla FreeS/WAN does not, but thanks to Mathieu Lafon and Arkoon
 Network Security, there's a patch to support this.</P>
<UL>
<LI><A HREF="http://open-source.arkoon.net">patch and documentation</A></LI>
<LI><A HREF="http://www.freeswan.ca">Super FreeS/WAN</A> incorporates
 this and other user-contributed patches.</LI>
</UL>
<P>The NAT traversal patch has some issues with PSKs, so you may wish to
 authenticate with RSA keys, or X.509 (requires a patch which is also
 included in Super FreeS/WAN). Doing the latter also has advantages when
 dealing with large numbers of clients who may be behind NAT; instead of
 having to make an individual Roadwarrior connection for each virtual
 IP, you can use the &quot;rightsubnetwithin&quot; parameter to specify a range.
 See<A HREF="http://www.strongsec.com/freeswan/install.htm#section_4.4">
 these<VAR> rightsubnetwithin</VAR> instructions</A>.</P>
<H3><A name="virtID">Does FreeS/WAN support assigning a &quot;virtual
 identity&quot; to a remote system?</A></H3>
<P>Some IPsec implementations allow you to make the source address on
 packets sent by a Road Warrior machine be something other than the
 address of its interface to the Internet. This is sometimes described
 as assigning a virtual identity to that machine.</P>
<P>FreeS/WAN does not directly support this, but it can be done. See
 this<A href="#road.masq"> FAQ question</A>.</P>
<H3><A name="noDES.faq">Does FreeS/WAN support single DES encryption?</A>
</H3>
<P><STRONG>No</STRONG>, single DES is not used either at the<A href="glossary.html#IKE">
 IKE</A> level for negotiating connections or at the<A href="glossary.html#IPsec">
 IPsec</A> level for actually building them.</P>
<P>Single DES is<A href="politics.html#desnotsecure"> insecure</A>. As
 we see it, it is more important to deliver real security than to comply
 with a standard which has been subverted into allowing use of
 inadequate methods. See this<A href="politics.html#weak"> discussion</A>
.</P>
<P>If you want to interoperate with an IPsec implementation which offers
 only DES, see our<A href="interop.html#noDES"> interoperation</A>
 document.</P>
<H3><A name="AES.faq">Does FreeS/WAN support AES encryption?</A></H3>
<P><A href="glossary.html#AES">AES</A> is a new US government<A href="glossary.html#block">
 block cipher</A> standard to replace the obsolete<A href="glossary.html#DES">
 DES</A>.</P>
<P>At time of writing (March 2002), the FreeS/WAN distribution does not
 yet support AES but user-written<A href="web.html#patch"> patches</A>
 are available to add it. Our kernel programmer is working on
 integrating those patches into the distribution, and there is active
 discussion of this on the design mailimg list.</P>
<H3><A name="other.cipher">Does FreeS/WAN support other encryption
 algorithms?</A></H3>
<P>Currently<A href="glossary.html#3DES"> triple DES</A> is the only
 cipher supported. AES will almost certainly be added (see previous
 question), and it is likely that in the process we will also add the
 other two AES finalists with open licensing, Twofish and Serpent.</P>
<P>We are extremely reluctant to add other ciphers. This would make both
 use and maintenance of FreeS/WAN more complex without providing any
 clear benefit. Complexity is emphatically not desirable in a security
 product.</P>
<P>Various users have written patches to add other ciphers. We provide<A href="web.html#patch">
 links</A> to these.</P>
<H2><A name="canI">Can I ...</A></H2>
<H3><A name="policy.preconfig">Can I use policy groups along with
 explicitly configured connections?</A></H3>
<P>Yes, you can, so long as you pay attention to the selection rule,
 which can be summarized &quot;the most specific connection wins&quot;. We
 describe the rule in our<A HREF="policygroups.html#policy.group.notes">
 policy groups</A> document, and provide a more technical explanation in<A
HREF="manpage.d/ipsec.conf.5.html"> man ipsec.conf</A>.</P>
<P>A good guideline: If you have a regular connection defined in<VAR>
 ipsec.conf</VAR>, ensure that a subset of that connection is not listed
 in a less restrictive policy group. Otherwise, FreeS/WAN will use the
 subset, with its more specific source/destination pair.</P>
<P>Here's an example. Suppose you are the system administrator at
 192.0.2.2. You have this connection in ipsec.conf:<VAR> ipsec.conf</VAR>
:</P>
<PRE>conn net-to-net
    left=192.0.2.2           # you are here
    right=192.0.2.8
    rightsubnet=192.0.2.96/27
    ....
</PRE>
<P>If you then place a host or net within<VAR> rightsubnet</VAR>, (let's
 say 192.0.2.98) in<VAR> private-or-clear</VAR>, you may find that
 192.0.2.2 at times communicates in the clear with 192.0.2.98. That's
 consistent with the rule, but may be contrary to your expectations.</P>
<P>On the other hand, it's safe to put a larger subnet in a less
 restrictive policy group file. If<VAR> private-or-clear</VAR> contains
 192.0.2.0/24, then the more specific<VAR> net-to-net</VAR> connection
 is used for any communication to 192.0.2.96/27. The more general policy
 applies only to communication with hosts or subnets in 192.0.2.0/24
 without a more specific policy or connection.</P>
<H3><A name="policy.off">Can I turn off policy groups?</A></H3>
<P>Yes. Use<A HREF="policygroups.html#disable_policygroups"> these
 instructions</A>.</P>

<!--
<h3><a name="policy.otherinterface">Can I use policy groups
 on an interface other than <VAR>%defaultroute</VAR>?</a></h3>

<p>??<p>
-->
<H3><A name="reload">Can I reload connection info without restarting?</A>
</H3>
<P>Yes, you can do this. Here are the details, in a mailing list message
 from Pluto programmer Hugh Redelmeier:</P>
<PRE>| How can I reload config's without restarting all of pluto and klips?  I am using
| FreeSWAN -&gt; PGPNet in a medium sized production environment, and would like to be
| able to add new connections ( i am using include config/* ) without dropping current
| SA's.
| 
| Can this be done?
| 
| If not, are there plans to add this kind of feature?

        ipsec auto --add whatever
This will look in the usual place (/etc/ipsec.conf) for a conn named
whatever and add it.

If you added new secrets, you need to do
        ipsec auto --rereadsecrets
before Pluto needs to know those secrets.

| I have looked (perhaps not thoroughly enough tho) to see how to do this:

There may be more bits to look for, depending on what you are trying
to do.</PRE>
<P>Another useful command here is<VAR> ipsec auto --replace &lt;conn_name&gt;</VAR>
 which re-reads data for a named connection.</P>
<H3><A name="masq.faq">Can I use several masqueraded subnets?</A></H3>
<P>Yes. This is done all the time. See the discussion in our<A href="config.html#route_or_not">
 setup</A> document. The only restriction is that the subnets on the two
 ends must not overlap. See the next question.</P>
<P>Here is a mailing list message on the topic. The user incorrectly
 thinks you need a 2.4 kernel for this -- actually various people have
 been doing it on 2.0 and 2.2 for quite some time -- but he has it right
 for 2.4.</P>
<PRE>Subject: Double NAT and freeswan working :)
   Date: Sun, 11 Mar 2001
   From: Paul Wouters &lt;paul@xtdnet.nl&gt;

Just to share my pleasure, and make an entry for people who are searching
the net on how to do this. Here's the very simple solution to have a double
NAT'ed network working with freeswan. (Not sure if this is old news, but I'm
not on the list (too much spam) and I didn't read this in any HOWTO/FAQ/doc
on the freeswan site yet (Sandy, put it in! :)

10.0.0.0/24 --- 10.0.0.1 a.b.c.d  ---- a.b.c.e {internet} ----+
                                                              |
10.0.1.0/24 --- 10.0.1.1 f.g.h.i  ---- f.g.h.j {internet} ----+

the goal is to have the first network do a VPN to the second one, yet also
have NAT in place for connections not destinated for the other side of the
NAT. Here the two Linux security gateways have one real IP number (cable
modem, dialup, whatever.

The problem with NAT is you don't want packets from 10.*.*.* to 10.*.*.*
to be NAT'ed. While with Linux 2.2, you can't, with Linux 2.4 you can.

(This has been tested and works for 2.4.2 with Freeswan snapshot2001mar8b)

relevant parts of /etc/ipsec.conf:

        left=f.g.h.i
        leftsubnet=10.0.1.0/24
        leftnexthop=f.g.h.j
        leftfirewall=yes
        leftid=@firewall.netone.nl
        leftrsasigkey=0x0........
        right=a.b.c.d
        rightsubnet=10.0.0.0/24
        rightnexthop=a.b.c.e
        rightfirewall=yes
        rightid=@firewall.nettwo.nl
        rightrsasigkey=0x0......
        # To authorize this connection, but not actually start it, at startup,
        # uncomment this.
        auto=add

and now the real trick. Setup the NAT correctly on both sites:

iptables -t nat -F
iptables -t nat -A POSTROUTING -o eth0 -d \! 10.0.0.0/8 -j MASQUERADE

This tells the NAT code to only do NAT for packets with destination other then
10.* networks. note the backslash to mask the exclamation mark to protect it
against the shell.

Happy painting :)

Paul</PRE>
<H3><A name="dup_route">Can I use subnets masqueraded to the same
 addresses?</A></H3>
<P><STRONG>No.</STRONG> The notion that IP addresses are unique is one
 of the fundamental principles of the IP protocol. Messing with it is
 exceedingly perilous.</P>
<P>Fairly often a situation comes up where a company has several
 branches, all using the same<A href="glossary.html#non-routable">
 non-routable addresses</A>, perhaps 192.168.0.0/24. This works fine as
 long as those nets are kept distinct. The<A href="glossary.html#masq">
 IP masquerading</A> on their firewalls ensures that packets reaching
 the Internet carry the firewall address, not the private address.</P>
<P>This can break down when IPsec enters the picture. FreeS/WAN builds a
 tunnel that pokes through both masquerades and delivers packets from<VAR>
 leftsubnet</VAR> to<VAR> rightsubnet</VAR> and vice versa. For this to
 work, the two subnets<EM> must</EM> be distinct.</P>
<P>There are several solutions to this problem.</P>
<P>Usually, you<STRONG> re-number the subnets</STRONG>. Perhaps the
 Vancouver office becomes 192.168.101.0/24, Calgary 192.168.102.0/24 and
 so on. FreeS/WAN can happily handle this. With, for example<VAR>
 leftsubnet=192.168.101.0/24</VAR> and<VAR> rightsubnet=192.168.102.0/24</VAR>
 in a connection description, any machine in Calgary can talk to any
 machine in Vancouver. If you want to be more restrictive and use
 something like<VAR> leftsubnet=192.168.101.128/25</VAR> and<VAR>
 rightsubnet=192.168.102.240/28</VAR> so only certain machines on each
 end have access to the tunnel, that's fine too.</P>
<P>You could also<STRONG> split the subnet</STRONG> into smaller ones,
 for example using<VAR> 192.168.1.0/25</VAR> in Vancouver and<VAR>
 rightsubnet=192.168.0.128/25</VAR> in Calgary.</P>
<P>Alternately, you can just<STRONG> give up routing</STRONG> directly
 to machines on the subnets. Omit the<VAR> leftsubnet</VAR> and<VAR>
 rightsubnet</VAR> parameters from your connection descriptions. Your
 IPsec tunnels will then run between the public interfaces of the two
 firewalls. Packets will be masqueraded both before they are put into
 tunnels and after they emerge. Your Vancouver client machines will see
 only one Calgary machine, the firewall.</P>
<H3><A name="road.masq">Can I assign a road warrior an address on my net
 (a virtual identity)?</A></H3>
<P>Often it would be convenient to be able to give a Road Warrior an IP
 address which appears to be on the local network. Some IPsec
 implementations have support for this, sometimes calling the feature
 &quot;virtual identity&quot;.</P>
<P>Currently (Sept 2002) FreeS/WAN does not support this, and we have no
 definite plans to add it. The difficulty is that is not yet a standard
 mechanism for it. There is an Internet Draft for a method of doing it
 using<A href="glossary.html#DHCP"> DHCP</A> which looks promising.
 FreeS/WAN may support that in a future release.</P>
<P>In the meanwhile, you can do it yourself using the Linux iproute2(8)
 facilities. Details are in<A href="http://www.av8n.com/vpn/iproute2.htm">
 this paper</A>.</P>
<P>Another method has also been discussed on the mailing list.:</P>
<UL>
<LI>You can use a variant of the<A href="adv_config.html#extruded.config">
 extruded subnet</A> procedure.</LI>
<LI>You have to avoid having the road warrior's assigned address within
 the range you actually use at home base. See previous question.</LI>
<LI>On the other hand, you want the roadwarrior's address to be within
 the range that<EM> seems</EM> to be on your network.</LI>
</UL>
<P>For example, you might have:</P>
<DL>
<DT>leftsubnet=a.b.c.0/25</DT>
<DD>head office network</DD>
<DT>rightsubnet=a.b.c.129/32</DT>
<DD>extruded to a road warrior. Note that this is not in a.b.c.0/25</DD>
<DT>a.b.c.0/24</DT>
<DD>whole network, including both the above</DD>
</DL>
<P>You then set up routing so that the office machines use the IPsec
 gateway as their route to a.b.c.128/25. The leftsubnet parameter tells
 the road warriors to use tunnels to reach a.b.c.0/25, so you should
 have two-way communication. Depending or your network and applications,
 there may be some additional work to do on DNS or Windows configuration</P>
<H3><A name="road.many">Can I support many road warriors with one
 gateway?</A></H3>
<P>Yes. This is easily done, using</P>
<DL>
<DT>either RSA authentication</DT>
<DD>standard in the FreeS/WAN distribution</DD>
<DT>or X.509 certificates</DT>
<DD>requires<A href="#PKIcert"> Super FreeS/WAN or a patch</A>.</DD>
</DL>
<P>In either case, each Road Warrior must have a different key or
 certificate.</P>
<P>It is also possible using pre-shared key authentication, though we
 don't recommend this; see the<A href="#road.PSK"> next question</A> for
 details.</P>
<P>If you expect to have more than a few dozen Road Warriors connecting
 simultaneously, you may need a fairly powerful gateway machine. See our
 document on<A href="performance.html"> FreeS/WAN performance</A>.</P>
<H3><A name="road.PSK">Can I have many road warriors using shared secret
 authentication?</A></H3>
<P><STRONG>Yes, but avoid it if possible</STRONG>.</P>
<P>You can have multiple Road Warriors using shared secret
 authentication<STRONG> only if they all use the same secret</STRONG>.
 You must also set:</P>
<P></P>
<PRE>   uniqueids=no   </PRE>
<P>in the connection definition.</P>
<P>Why it's less secure:</P>
<UL>
<LI>If you have many users, it becomes almost certain the secret will
 leak</LI>
<LI>The secret becomes quite valuable to an attacker</LI>
<LI>All users authenticate the same way, so the gateway cannot tell them
 apart for logging or access control purposes</LI>
<LI>Changing the secret is difficult. You have to securely notify all
 users.</LI>
<LI>If you find out the secret has been compromised, you can change it,
 but then what? None of your users can connect without the new secret.
 How will you notify them all, quickly and securely, without using the
 VPN?</LI>
</UL>
<P>This is a designed-in limitation of the<A href="glossary.html#IKE">
 IKE</A> key negotiation protocol, not a problem with our
 implementation.</P>
<P><STRONG>We very strongly recommend that you avoid using shared secret
 authentication for multiple Road Warriors.</STRONG> Use RSA
 authentication instead.</P>
<P>The longer story: When using shared secrets, the protocol requires
 that the responding gateway be able to determine which secret to use at
 a time when all it knows about the initiator is an IP address. This
 works fine if you know the initiator's address in advance and can use
 it to look up the appropiriate secret. However, it fails for Road
 Warriors since the gateway cannot know their IP addresses in advance.</P>
<P>With RSA signatures (or certificates) the protocol is slightly
 different. The initiator provides an identifier early in the exchange
 and the responder can use that identifier to look up the correct key or
 certificate. See<A href="#road.many"> above</A>.</P>
<H3><A name="QoS">Can I use Quality of Service routing with FreeS/WAN?</A>
</H3>
<P>From project technical lead Henry Spencer:</P>
<PRE>&gt; Do QoS add to FreeS/WAN?
&gt; For example integrating DiffServ and FreeS/WAN?

With a current version of FreeS/WAN, you will have to add hidetos=no to
the config-setup section of your configuration file.  By default, the TOS
field of tunnel packets is zeroed; with hidetos=no, it is copied from the
packet inside.  (This is a modest security hole, which is why it is no
longer the default.)

DiffServ does not interact well with tunneling in general.  Ways of
improving this are being studied.</PRE>
<P>Copying the<A href="glossary.html#TOS"> TOS</A> (type of service)
 information from the encapsulated packet to the outer header reveals
 the TOS information to an eavesdropper. This does not tell him much,
 but it might be of use in<A href="glossary.html#traffic"> traffic
 analysis</A>. Since we do not have to give it to him, our default is
 not to.</P>
<P>Even with the TOS hidden, you can still:</P>
<UL>
<LI>apply QOS rules to the tunneled (ESP) packets; for example, by
 giving ESP packets a certain priority.</LI>
<LI>apply QOS rules to the packets as they enter or exit the tunnel via
 an IPsec virtual interface (eg.<VAR> ipsec0</VAR>).</LI>
</UL>
<P>See<A href="manpage.d/ipsec.conf.5.html"> ipsec.conf(5)</A> for more
 on the<VAR> hidetos=</VAR> parameter.</P>
<H3><A name="deadtunnel">Can I recognise dead tunnels and shut them
 down?</A></H3>
<P>There is no general mechanism to do this is in the IPsec protocols.</P>
<P>From time to time, there is discussion on the IETF Working Group<A href="mail.html#ietf">
 mailing list</A> of adding a &quot;keep-alive&quot; mechanism (which some say
 should be called &quot;make-dead&quot;), but it is a fairly complex problem and
 no consensus has been reached on whether or how it should be done.</P>
<P>The protocol does have optional<A href="#ignore"> delete-SA</A>
 messages which one side can send when it closes a connection in hopes
 this will cause the other side to do the same. FreeS/WAN does not
 currently support these. In any case, they would not solve the problem
 since:</P>
<UL>
<LI>a gateway that crashes or hangs would not send the messages</LI>
<LI>the sender is not required to send them</LI>
<LI>they are not authenticated, so any receiver that trusts them leaves
 itself open to a<A href="glossary.html#DOS"> denial of service</A>
 attack</LI>
<LI>the receiver is not required to do anything about them</LI>
<LI>the receiver cannot acknowledge them; the protocol provides no
 mechanism for that</LI>
<LI>since they are not acknowledged, the sender cannot rely on them</LI>
</UL>
<P>However, connections do have limited lifetimes and you can control
 how many attempts your gateway makes to rekey before giving up. For
 example, you can set:</P>
<PRE>conn default
        keyingtries=3
        keylife=30m</PRE>
<P>With these settings old connections will be cleaned up. Within 30
 minutes of the other end dying, rekeying will be attempted. If it
 succeeds, the new connection replaces the old one. If it fails, no new
 connection is created. Either way, the old connection is taken down
 when its lifetime expires.</P>
<P>Here is a mailing list message on the topic from FreeS/WAN tech
 support person Claudia Schmeing:</P>
<PRE>You ask how to determine whether a tunnel is redundant:

&gt; Can anybody explain the best way to determine this. Esp when a RW has
&gt; disconnected? I thought 'ipsec auto --status' might be one way.

If a tunnel goes down from one end, Linux FreeS/WAN on the
other end has no way of knowing this until it attempts to rekey.
Once it tries to rekey and fails, it will 'know' that the tunnel is 
down.

Because it doesn't have a way of knowing the state until this point, 
it will also not be able to tell you the state via ipsec auto --status.

&gt; However, comparing output from a working tunnel with that of one that
&gt; was closed 
&gt; did not show clearly show tunnel status.

If your tunnel is down but not 'unrouted' (see man ipsec_auto), you
should not be able to ping the opposite side of the tunnel. You can
use this as an indicator of tunnel status.

On a related note, you may be interested to know that as of 1.7, 
redundant tunnels caused by RW disconnections are likely to be 
less of a pain. From doc/CHANGES:

    There is a new configuration parameter, uniqueids, to control a new Pluto
    option:  when a new connection is negotiated with the same ID as an old
    one, the old one is deleted immediately.  This should help eliminate
    dangling Road Warrior connections when the same Road Warrior reconnects. 
    It thus requires that IDs not be shared by hosts (a previously legal but
    probably useless capability).  NOTE WELL:  the sample ipsec.conf now has
    uniqueids=yes in its config-setup section.


Cheers,

Claudia</PRE>
<H3><A name="demanddial">Can I build IPsec tunnels over a demand-dialed
 link?</A></H3>
<P>This is possible, but not easy. FreeS/WAN technical lead Henry
 Spencer wrote:</P>
<PRE>&gt; 5. If the ISDN link goes down in between and is reestablished, the SAs
&gt; are still up but the eroute are deleted and the IPsec interface shows
&gt; garbage (with ifconfig)
&gt; 6. Only restarting IPsec will bring the VPN back online.

This one is awkward to solve.  If the real interface that the IPsec
interface is mounted on goes down, it takes most of the IPsec machinery
down with it, and a restart is the only good way to recover. 

The only really clean fix, right now, is to split the machines in two: 

1. A minimal machine serves as the network router, and only it is aware
that the link goes up and down. 

2. The IPsec is done on a separate gateway machine, which thinks it has
a permanent network connection, via the router.

This is clumsy but it does work.  Trying to do both functions within a
single machine is tricky.  There is a software package (diald) which will
give the illusion of a permanent connection for demand-dialed modem
connections; I don't know whether it's usable for ISDN, or whether it can
be made to cooperate properly with FreeS/WAN. 

Doing a restart each time the interface comes up *does* work, although it
is a bit painful.  I did that with PPP when I was running on a modem link;
it wasn't hard to arrange the PPP scripts to bring IPsec up and down at
the right times.  (I'd meant to investigate diald but never found time.)

In principle you don't need to do a complete restart on reconnect, but you
do have to rebuild some things, and we have no nice clean way of doing
only the necessary parts.</PRE>
<P>In the same thread, one user commented:</P>
<PRE>Subject: Re: linux-ipsec: IPsec and Dial Up Connections
   Date: Wed, 22 Nov 2000
   From: Andy Bradford &lt;andyb@calderasystems.com&gt;

On Wed, 22 Nov 2000 19:47:11 +0100, Philip Reetz wrote:

&gt; Are there any ideas what might be the cause of the problem and any way
&gt; to work around it.
&gt; Any help is highly appreciated.

On my laptop, when using ppp there is a ip-up script in /etc/ppp that 
will be executed each time that the ppp interface is brought up.  
Likewise there is an ip-down script that is called when it is taken 
down.  You might consider custimzing those to stop and start FreeS/WAN 
with each connection.  I believe that ISDN uses the same files, though 
I could be wrong---there should be something similar though.</PRE>
<H3><A name="GRE">Can I build GRE, L2TP or PPTP tunnels over IPsec?</A></H3>
<P>Yes. Normally this is not necessary, but it is useful in a few
 special cases. For example, if you must route non-IP packets such as
 IPX, you will need to use a tunneling protocol that can route these
 packets. IPsec can be layered around it for extra security. Another
 example: you can provide failover protection for high availability (HA)
 environments by combining IPsec with other tools. Ken Bantoft describes
 one such setup in<A HREF="http://www.freeswan.ca/docs/HA"> Using
 FreeS/WAN with Linux-HA, GRE, OSPF and BGP for enterprise grade VPN
 solutions</A>.</P>
<P>GRE over IPsec is covered as part of<A HREF="http://www.freeswan.ca/docs/HA">
 that document</A>.<A href="http://www.sandelman.ottawa.on.ca/linux-ipsec/html/2000/07/msg00209.html">
 Here are links</A> to other GRE resources. Jacco de Leuw has created<A HREF="http://www.jacco2.dds.nl/networking/">
 this page on L2TP over IPsec</A> with instructions for FreeS/WAN and
 several other brands of IPsec software.</P>
<P>Please let us know of other useful links via the<A HREF="mail.html">
 mailing lists</A>.</P>
<H3><A name="NetBIOS">... use Network Neighborhood (Samba, NetBIOS) over
 IPsec?</A></H3>
<P>Your local PC needs to know how to translate NetBIOS names to IP
 addresses. It may do this either via a local LMHOSTS file, or using a
 local or remote WINS server. The WINS server is preferable since it
 provides a centralized source of the information to the entire network.
 To use a WINS server over the<A HREF="glossary.html#VPN"> VPN</A> (or
 any IP-based network), you must enable &quot;NetBIOS over TCP&quot;.</P>
<P><A HREF="http://www.samba.org">Samba</A> can emulate a WINS server on
 Linux.</P>
<P> See also several discussions in our<A HREF="http://lists.freeswan.org/pipermail/users/2002-September/thread.html">
 September 2002 Users archives</A></P>
<H2><A name="setup.faq">Life's little mysteries</A></H2>
<P>FreeS/WAN is a fairly complex product. (Neither the networks it runs
 on nor the protocols it uses are simple, so it could hardly be
 otherwise.) It therefore sometimes exhibits behaviour which can be
 somewhat confusing, or has problems which are not easy to diagnose.
 This section tries to explain those problems.</P>
<P>Setup and configuration of FreeS/WAN are covered in other
 documentation sections:</P>
<UL>
<LI><A href="quickstart.html">basic setup and configuration</A></LI>
<LI><A href="adv_config.html">advanced configuration</A></LI>
<LI><A href="trouble.html">Troubleshooting</A></LI>
</UL>
<P>However, we also list some of the commonest problems here.</P>
<H3><A name="cantping">I cannot ping ....</A></H3>
<P>This question is dealt with in the advanced configuration section
 under the heading<A href="adv_config.html#multitunnel"> multiple
 tunnels</A>.</P>
<P>The standard subnet-to-subnet tunnel protects traffic<STRONG> only
 between the subnets</STRONG>. To test it, you must use pings that go
 from one subnet to the other.</P>
<P>For example, suppose you have:</P>
<PRE>      subnet a.b.c.0/24
             |
      eth1 = a.b.c.1
         gate1
      eth0 = 192.0.2.8
             |

       ~ internet ~

             |
      eth0 = 192.0.2.11
         gate2
      eth1 = x.y.z.1
              |
       subnet x.y.z.0/24</PRE>
<P>and the connection description:</P>
<PRE>conn abc-xyz
     left=192.0.2.8
     leftsubnet=a.b.c.0/24
     right=192.0.2.11
     rightsubnet=x.y.z.0/24</PRE>
<P>You can test this connection description only by sending a ping that
 will actually go through the tunnel. Assuming you have machines at
 addresses a.b.c.2 and x.y.z.2, pings you might consider trying are:</P>
<DL>
<DT>ping from x.y.z.2 to a.b.c.2 or vice versa</DT>
<DD>Succeeds if tunnel is working. This is the<STRONG> only valid test
 of the tunnel</STRONG>.</DD>
<DT>ping from gate2 to a.b.c.2 or vice versa</DT>
<DD><STRONG>Does not use tunnel</STRONG>. gate2 is not on protected
 subnet.</DD>
<DT>ping from gate1 to x.y.z.2 or vice versa</DT>
<DD><STRONG>Does not use tunnel</STRONG>. gate1 is not on protected
 subnet.</DD>
<DT>ping from gate1 to gate2 or vice versa</DT>
<DD><STRONG>Does not use tunnel</STRONG>. Neither gate is on a protected
 subnet.</DD>
</DL>
<P>Only the first of these is a useful test of this tunnel. The others
 do not use the tunnel. Depending on other details of your setup and
 routing, they:</P>
<UL>
<LI>either fail, telling you nothing about the tunnel</LI>
<LI>or succeed, telling you nothing about the tunnel since these packets
 use some other route</LI>
</UL>
<P>In some cases, you may be able to get around this. For the example
 network above, you could use:</P>
<PRE>        ping -I a.b.c.1 x.y.z.1</PRE>
<P>Both the adresses given are within protected subnets, so this should
 go through the tunnel.</P>
<P>If required, you can build additional tunnels so that all the
 machines involved can talk to all the others. See<A href="adv_config.html#multitunnel">
 multiple tunnels</A> in the advanced configuration document for
 details.</P>
<H3><A name="forever">It takes forever to ...</A></H3>
<P>Users fairly often report various problems involving long delays,
 sometimes on tunnel setup and sometimes on operations done through the
 tunnel, occasionally on simple things like ping or more often on more
 complex operations like doing NFS or Samba through the tunnel.</P>
<P>Almost always, these turn out to involve failure of a DNS lookup. The
 timeouts waiting for DNS are typically set long so that you won't time
 out when a query involves multiple lookups or long paths. Genuine
 failures therefore produce long delays before they are detected.</P>
<P>A mailing list message from project technical lead Henry Spencer:</P>
<PRE>&gt; ... when i run /etc/rc.d/init.d/ipsec start, i get:
&gt; ipsec_setup: Starting FreeS/WAN IPsec 1.5...
&gt; and it just sits there, doesn't give back my bash prompt.

Almost certainly, the problem is that you're using DNS names in your
ipsec.conf, but DNS lookups are not working for some reason.  You will
get your prompt back... eventually.  But the DNS timeouts are long.
Doing something about this is on our list, but it is not easy.</PRE>
<P>In the meanwhile, we recommend that connection descriptions in<A href="manpage.d/ipsec.conf.5.html">
 ipsec.conf(5)</A> use numeric IP addresses rather than names which will
 require a DNS lookup.</P>
<P>Names that do not require a lookup are fine. For example:</P>
<UL>
<LI>a road warrior might use the identity<VAR>
 rightid=@lancelot.example.org</VAR></LI>
<LI>the gateway might use<VAR> leftid=@camelot.example.org</VAR></LI>
</UL>
<P>These are fine. The @ sign prevents any DNS lookup. However, do not
 attempt to give the gateway address as<VAR> left=camelot.example.org</VAR>
. That requires a lookup.</P>
<P>A post from one user after solving a problem with long delays:</P>
<PRE>Subject: Final Answer to Delay!!!
   Date: Mon, 19 Feb 2001
   From: &quot;Felippe Solutions&quot; &lt;felippe@solutionstecnologia.com.br&gt;

Sorry people, but seems like the Delay problem had nothing to do with
freeswan.

The problem was DNS as some people sad from the beginning, but not the way
they thought it was happening. Samba, ssh, telnet and other apps try to
reverse lookup addresses when you use IP numbers (Stupid that ahh).

I could ping very fast because I always ping with &quot;-n&quot; option, but I don't
know the option on the other apps to stop reverse addressing so I don't use
it.</PRE>
<P>This post is fairly typical. These problems are often tricky and
 frustrating to diagnose, and most turn out to be DNS-related.</P>
<P>One suggestion for diagnosis: test with both names and addresses if
 possible. For example, try all of:</P>
<UL>
<LI>ping<VAR> address</VAR></LI>
<LI>ping -n<VAR> address</VAR></LI>
<LI>ping<VAR> name</VAR></LI>
</UL>
<P>If these behave differently, the problem must be DNS-related since
 the three commands do exactly the same thing except for DNS lookups.</P>
<H3><A name="route">I send packets to the tunnel with route(8) but they
 vanish</A></H3>
<P>IPsec connections are designed to carry only packets travelling
 between pre-defined connection endpoints. As project technical lead
 Henry Spencer put it:</P>
<BLOCKQUOTE> IPsec tunnels are not just virtual wires; they are virtual
 wires with built-in access controls. Negotiation of an IPsec tunnel
 includes negotiation of access rights for it, which don't include
 packets to/from other IP addresses. (The protocols themselves are quite
 inflexible about this, so there are limits to what we can do about it.)</BLOCKQUOTE>
<P>For fairly obvious security reasons, and to comply with the IPsec
 RFCs,<A href="glossary.html#KLIPS"> KLIPS</A> drops any packets it
 receives that are not allowed on the tunnels currently defined. So if
 you send it packets with<VAR> route(8)</VAR>, and suitable tunnels are
 not defined, the packets vanish. Whether this is reported in the logs
 depends on the setting of<VAR> klipsdebug</VAR> in your<A href="manpage.d/ipsec.conf.5.html">
 ipsec.conf(5)</A> file.</P>
<P>To rescue vanishing packets, you must ensure that suitable tunnels
 for them exist, by editing the connection descriptions in<A href="manpage.d/ipsec.conf.5.html">
 ipsec.conf(5)</A>. For example, supposing you have a simple setup:</P>
<PRE>         leftsubnet -- leftgateway === internet === roadwarrior</PRE>
<P>If you want to give the roadwarrior access to some resource that is
 located behind the left gateway but is not in the currently defined
 left subnet, then the usual procedure is to define an additional tunnel
 for those packets by creating a new connection description.</P>
<P>In some cases, it may be easier to alter an existing connection
 description, enlarging the definition of<VAR> leftsubnet</VAR>. For
 example, instead of two connection descriptions with 192.168.8.0/24 and
 192.168.9.0/24 as their<VAR> leftsubnet</VAR> parameters, you can use a
 single description with 192.168.8.0/23.</P>
<P>If you have multiple endpoints on each side, you need to ensure that
 there is a route for each pair of endpoints. See this<A href="adv_config.html#multitunnel">
 example</A>.</P>
<H3><A name="down_route">When a tunnel goes down, packets vanish</A></H3>
<P>This is a special case of the vanishing packet problem described in
 the previous question. Whenever KLIPS sees packets for which it does
 not have a tunnel, it drops them.</P>
<P>When a tunnel goes away, either because negotiations with the other
 gateway failed or because you gave an<VAR> ipsec auto --down</VAR>
 command, the route to its other end is left pointing into KLIPS, and
 KLIPS will drop packets it has no tunnel for.</P>
<P>This is a documented design decision, not a bug. FreeS/WAN must not
 automatically adjust things to send packets via another route. The
 other route might be insecure.</P>
<P>Of course, re-routing may be necessary in many cases. In those cases,
 you have to do it manually or via scripts. We provide the<VAR> ipsec
 auto --unroute</VAR> command for these cases.</P>
<P>From<A href="manpage.d/ipsec_auto.8.html"> ipsec_auto(8)</A>:</P>
<BLOCKQUOTE> Normally, pluto establishes a route to the destination
 specified for a connection as part of the --up operation. However, the
 route and only the route can be established with the --route operation.
 Until and unless an actual connection is established, this discards any
 packets sent there, which may be preferable to having them sent
 elsewhere based on a more general route (e.g., a default route).</BLOCKQUOTE><BLOCKQUOTE>
 Normally, pluto's route to a destination remains in place when a --down
 operation is used to take the connection down (or if connection setup,
 or later automatic rekeying, fails). This permits establishing a new
 connection (perhaps using a different specification; the route is
 altered as necessary) without having a ``window'' in which packets
 might go elsewhere based on a more general route. Such a route can be
 removed using the --unroute operation (and is implicitly removed by
 --delete).</BLOCKQUOTE>
<P>See also this mailing list<A href="http://www.sandelman.ottawa.on.ca/linux-ipsec/html/2000/11/msg00523.html">
 message</A>.</P>
<H3><A name="firewall_ate">The firewall ate my packets!</A></H3>
<P>If firewalls filter out:</P>
<UL>
<LI>either the UDP port 500 packets used in IKE negotiations</LI>
<LI>or the ESP and AH (protocols 50 and 51) packets used to implement
 the IPsec tunnel</LI>
</UL>
<P>then IPsec cannot work. The first thing to check if packets seem to
 be vanishing is the firewall rules on the two gateway machines and any
 other machines along the path that you have access to.</P>
<P>For details, see our document on<A href="firewall.html"> firewalls</A>
.</P>
<P>Some advice from technical lead Henry Spencer on diagnosing such
 problems:</P>
<PRE>&gt; &gt; Packets vanishing between the hardware interface and the ipsecN interface
&gt; &gt; is usually the result of firewalls not being configured to let them in...
&gt; 
&gt; Thanks for the suggestion. If only it were that simple! My ipchains startup
&gt; script does take care of that, but just in case I manually inserted rules 
&gt; accepting everything from london on dublin. No difference.

The other thing to check is whether the &quot;RX packets dropped&quot; count on the
ipsecN interface (run &quot;ifconfig ipsecN&quot;, for N=1 or whatever, to see the
counts) is rising.  If so, then there's some sort of configuration mismatch
between the two ends, and IPsec itself is rejecting them.  If none of the
ipsecN counts is rising, then the packets are never reaching the IPsec
machinery, and the problem is almost certainly in firewalls etc.</PRE>
<H3><A name="dropconn">Dropped connections</A></H3>
<P>Networks being what they are, IPsec connections can be broken for any
 number of reasons, ranging from hardware failures to various software
 problems such as the path MTU problems discussed<A href="#pmtu.broken">
 elsewhere in the FAQ</A>. Fortunately, various diagnostic tools exist
 that help you sort out many of the possible problems.</P>
<P>There is one situation, however, where FreeS/WAN (using default
 settings) may destroy a connection for no readily apparent reason. This
 occurs when things are<STRONG> misconfigured</STRONG> so that<STRONG>
 two tunnels</STRONG> from the same gateway expect<STRONG> the same
 subnet on the far end</STRONG>.</P>
<P>In this situation, the first tunnel comes up fine and works until the
 second is established. At that point, because of the way we track
 connections internally, the first tunnel ceases to exist as far as this
 gateway is concerned. Of course the far end does not know that, and a
 storm of error messages appears on both systems as it tries to use the
 tunnel.</P>
<P>If the far end gives up, goes back to square one and negotiates a new
 tunnel, then that wipes out the second tunnel and ...</P>
<P>The solution is simple.<STRONG> Do not build multiple conn
 descriptions with the same remote subnet</STRONG>.</P>
<P>This is actually intended to be a feature, rather than a bug.
 Consider the situation where a single remote system goes down, then
 comes back up and reconnects to the gateway. It is useful to have the
 gateway tear down the old tunnel and recover resources when the
 reconnection is made. It recognises that situation by checking the
 remote subnet for each tunnel it builds and discarding duplicates. This
 works fine as long as you don't configure multiple tunnels with the
 same remote subnet.</P>
<P>If this behaviour is inconvenient for you, you can disable it by
 setting<VAR> uniqueids=no</VAR> in<A href="manpage.d/ipsec.conf.5.html">
 ipsec.conf(5)</A>.</P>
<H3><A name="defaultroutegone">Disappearing %defaultroute</A></H3>
<P>When an underlying connection (eg. ppp) goes down, FreeS/WAN will not
 recover properly without a little help. Here are the symptoms that
 FreeS/WAN user Michael Carmody noticed:</P>
<PRE>
&gt; After about 24 hours the freeswan connection takes over the default route.
&gt; 
&gt; i.e instead of deafult gateway pointing to the router via eth0, it becomes a 
&gt; pointer to the router via ipsec0.
 
&gt; All internet access is then lost as all replies (and not just the link I 
&gt; wanted) are routed out ipsec0 and the router doesn't respond to the ipsec 
&gt; traffic.
</PRE>
<P>If you're using a FreeS/WAN 2.x/KLIPS system, simply re-attach the
 IPsec virtual interface with<EM> ipsec tnconfig</EM> command such as:</P>
<PRE>    ipsec tnconfig --attach --virtual ipsec0 --physical ppp0</PRE>
<P>In your command, name the physical and virtual interfaces as they
 appear paired on your system during regular uptime. For a system with
 several physical/virtual interface pairs on flaky links, you'll need
 more than one such command. If you're using FreeS/WAN 1.x, you must
 restart FreeS/WAN, which is more time consuming.</P>
<P><A href="http://lists.freeswan.org/pipermail/design/2002-July/003070.html">
 Here</A> is a script which can help to automate the process of
 FreeS/WAN restart at need. It could easily be adapted to use tnconfig
 instead.</P>
<H3><A name="tcpdump.faq">TCPdump on the gateway shows strange things</A>
</H3>
 As another user pointed out, keeping the connect
<P>Attempting to look at IPsec packets by running monitoring tools on
 the IPsec gateway machine can produce silly results. That machine is
 mangling the packets for IPsec, and possibly for firewall or NAT
 purposes as well. If the internals of the machine's IP stack are not
 what the monitoring tool expects, then the tool can misinterpret them
 and produce nonsense output.</P>
<P>See our<A href="testing.html#tcpdump.test"> testing</A> document for
 more detail.</P>
<H3><A name="no_trace">Traceroute does not show anything between the
 gateways</A></H3>
<P>As far as traceroute can see, the two gateways are one hop apart; the
 data packet goes directly from one to the other through the tunnel. Of
 course the outer packets that implement the tunnel pass through
 whatever lies between the gateways, but those packets are built and
 dismantled by the gateways. Traceroute does not see them and cannot
 report anything about their path.</P>
<P>Here is a mailing list message with more detail.</P>
<PRE>Date: Mon, 14 May 2001
To: linux-ipsec@freeswan.org
From: &quot;John S. Denker&quot; &lt;jsd@research.att.com&lt;
Subject: Re: traceroute: one virtual hop

At 02:20 PM 5/14/01 -0400, Claudia Schmeing wrote:
&gt;
&gt;&gt; &gt; A bonus question: traceroute in subnet to subnet enviroment looks like:
&gt;&gt; &gt; 
&gt;&gt; &gt; traceroute to andris.dmz (172.20.24.10), 30 hops max, 38 byte packets
&gt;&gt; &gt; 1  drama (172.20.1.1)  0.716 ms  0.942 ms  0.434 ms
&gt;&gt; &gt; 2  * * *
&gt;&gt; &gt; 3  andris.dmz (172.20.24.10)  73.576 ms  78.858 ms  79.434 ms
&gt;&gt; &gt; 
&gt;&gt; &gt; Why aren't there the other hosts which take part in the delivery during 
&gt;    * * * ?
&gt;
&gt;If there is an ipsec tunnel between GateA and Gate B, this tunnel forms a 
&gt;'virtual wire'.  When it is tunneled, the original packet becomes an inner 
&gt;packet, and new ESP and/or AH headers are added to create an outer packet 
&gt;around it. You can see an example of how this is done for AH at 
&gt;doc/ipsec.html#AH . For ESP it is similar.
&gt;
&gt;Think about the packet's path from the inner packet's perspective.
&gt;It leaves the subnet, goes into the tunnel, and re-emerges in the second
&gt;subnet. This perspective is also the only one available to the
&gt;'traceroute' command when the IPSec tunnel is up.

Claudia got this exactly right.  Let me just expand on a couple of points:

*) GateB is exactly one (virtual) hop away from GateA.  This is how it
would be if there were a physically private wire from A to B.  The
virtually private connection should work the same, and it does.

*) While the information is in transit from GateA to GateB, the hop count
of the outer header (the &quot;envelope&quot;) is being decremented.  The hop count
of the inner header (the &quot;contents&quot; of the envelope) is not decremented and
should not be decremented.  The hop count of the outer header is not
derived from and should not be derived from the hop count of the inner header.

Indeed, even if the packets did time out in transit along the tunnel, there
would be no way for traceroute to find out what happened.  Just as
information cannot leak _out_ of the tunnel to the outside, information
cannot leak _into_ the tunnel from outside, and this includes ICMP messages
from routers along the path.

There are some cases where one might wish for information about what is
happening at the IP layer (below the tunnel layer) -- but the protocol
makes no provision for this.  This raises all sorts of conceptual issues.
AFAIK nobody has ever cared enough to really figure out what _should_
happen, let alone implement it and standardize it.

*) I consider the &quot;* * *&quot; to be a slight bug.  One might wish for it to be
replaced by &quot;GateB GateB GateB&quot;.  It has to do with treating host-to-subnet
traffic different from subnet-to-subnet traffic (and other gory details).
I fervently hope KLIPS2 will make this problem go away.

*) If you want to ask questions about the link from GateA to GateB at the
IP level (below the tunnel level), you have to ssh to GateA and launch a
traceroute from there.</PRE>
<H2><A name="man4debug">Testing in stages</A></H2>
<P>It is often useful in debugging to test things one at a time:</P>
<UL>
<LI>disable IPsec entirely, for example by turning it off with
 chkconfig(8), and make sure routing works</LI>
<LI>Once that works, try a manually keyed connection. This does not
 require key negotiation between Pluto and the key daemon on the other
 end.</LI>
<LI>Once that works, try automatically keyed connections</LI>
<LI>Once IPsec works, add packet compression</LI>
<LI>Once everything seems to work, try stress tests with large
 transfers, many connections, frequent re-keying, ...</LI>
</UL>
<P>FreeS/WAN releases are tested for all of these, so you can be
 reasonably certain they<EM> can</EM> do them all. Of course, that does
 not mean they<EM> will</EM> on the first try, especially if you have
 some unusual configuration.</P>
<P>The rest of this section gives information on diagnosing the problem
 when each of the above steps fails.</P>
<H3><A name="nomanual">Manually keyed connections don't work</A></H3>
<P>Suspect one of:</P>
<UL>
<LI>mis-configuration of IPsec system in the /etc/ipsec.conf file
<BR> common errors are incorrect interface or next hop information</LI>
<LI>mis-configuration of manual connection in the /etc/ipsec.conf file</LI>
<LI>routing problems causing IPsec packets to be lost</LI>
<LI>bugs in KLIPS</LI>
<LI>mismatch between the transforms we support and those another IPsec
 implementation offers.</LI>
</UL>
<H3><A name="spi_error">One manual connection works, but second one
 fails</A></H3>
<P>This is a fairly common problem when attempting to configure multiple
 manually keyed connections from a single gateway.</P>
<P>Each connection must be identified by a unique<A href="glossary.html#SPI">
 SPI</A> value. For automatic connections, these values are assigned
 automatically. For manual connections, you must set them with<VAR> spi=</VAR>
 statements in<A href="manpage.d/ipsec.conf.5.html"> ipsec.conf(5)</A>.</P>
<P>Each manual connection must have a unique SPI value in the range
 0x100 to 0x999. Two or more with the same value will fail. For details,
 see our doc section<A href="adv_config.html#prodman"> Using manual
 keying in production</A> and the man page<A href="manpage.d/ipsec.conf.5.html">
 ipsec.conf(5)</A>.</P>
<H3><A name="man_no_auto">Manual connections work, but automatic keying
 doesn't</A></H3>
<P>The most common reason for this behaviour is a firewall dropping the
 UDP port 500 packets used in key negotiation.</P>
<P>Other possibilities:</P>
<UL>
<LI>mis-configuration of auto connection in the /etc/ipsec.conf file.
<P>One common configuration error is forgetting that you need<VAR>
 auto=add</VAR> to load the connection description on the receiving end
 so it recognises the connection when the other end asks for it.</P>
</LI>
<LI>error in shared secret in /etc/ipsec.secrets</LI>
<LI>one gateway lacks a route to the other so Pluto's UDP packets are
 lost</LI>
<LI>bugs in Pluto</LI>
<LI>incompatibilities between Pluto's<A href="glossary.html#IKE"> IKE</A>
 implementation and the IKE at the other end of the tunnel.
<P>Some possibile problems are discussed in out<A href="interop.html#interop.problem">
 interoperation</A> document.</P>
</LI>
</UL>
<H3><A name="nocomp">IPsec works, but connections using compression fail</A>
</H3>
<P>When we first added compression, we saw some problems:</P>
<UL>
<LI>compatibility issues with other implementations. We followed the
 RFCs and omitted some extra material that many compression libraries
 add by default. Some other implementations left the extras in</LI>
<LI>bugs in assembler compression routines on non-Intel CPUs. The
 workaround is to use C code instead of possibly problematic assembler.</LI>
</UL>
<P>We have not seen either problem in some time (at least six months as
 I write in March 2002), but if you have some unusual configuration then
 you may see them.</P>
<H3><A name="pmtu.broken">Small packets work, but large transfers fail</A>
</H3>
<P>If tests with ping(1) and a small packet size succeed, but tests or
 transfers with larger packet sizes fail, suspect problems with packet
 fragmentation and perhaps<A href="glossary.html#pathMTU"> path MTU
 discovery</A>.</P>
<P>Our<A href="trouble.html#bigpacket"> troubleshooting document</A>
 covers these problems. Information on the underlying mechanism is in
 our<A href="background.html#MTU.trouble"> background</A> document.</P>
<H3><A name="subsub">Subnet-to-subnet works, but tests from the gateways
 don't</A></H3>
<P>This is described under<A href="#cantping"> I cannot ping...</A>
 above.</P>
<H2><A name="compile.faq">Compilation problems</A></H2>
<H3><A name="gmp.h_missing">gmp.h: No such file or directory</A></H3>
<P>Pluto needs the GMP (<STRONG>G</STRONG>NU</P>
<P><STRONG>M</STRONG>ulti-<STRONG>P</STRONG>recision) library for the
 large integer calculations it uses in<A href="glossary.html#public">
 public key</A> cryptography. This error message indicates a failure to
 find the library. You must install it before Pluto will compile.</P>
<P>The GMP library is included in most Linux distributions. Typically,
 there are two RPMs, libgmp and libgmp-devel, You need to<EM> install
 both</EM>, either from your distribution CDs or from your vendor's web
 site.</P>
<P>On Debian, a mailing list message reports that the command to give is<VAR>
 apt-get install gmp2</VAR>.</P>
<P>For more information and the latest version, see the<A href="http://www.swox.com/gmp/">
 GMP home page</A>.</P>
<H3><A name="noVM">... virtual memory exhausted</A></H3>
<P>We have had several reports of this message appearing, all on SPARC
 Linux. Here is a mailing message on a solution:</P>
<PRE>&gt; ipsec_sha1.c: In function `SHA1Transform':
&gt; ipsec_sha1.c:95: virtual memory exhausted

I'm seeing exactly the same problem on an Ultra with 256MB ram and 500
MB swap.  Except I am compiling version 1.5 and its Red Hat 6.2.

I can get around this by using -O instead of -O2 for the optimization
level.  So it is probably a bug in the optimizer on the sparc complier. 
I'll try and chase this down on the sparc lists.</PRE>
<H2><A name="error">Interpreting error messages</A></H2>
<H3><A name="route-client">route-client (or host) exited with status 7</A>
</H3>
<P>Here is a discussion of this error from FreeS/WAN &quot;listress&quot; (mailing
 list tech support person) Claudia Schmeing. The &quot;FAQ on the network
 unreachable error&quot; which she refers to is the next question below.</P>
<PRE>&gt; I reached the point where the two boxes (both on dial-up connections, but
&gt; treated as static IPs by getting the IP and editing ipsec.conf after the
&gt; connection is established) to the point where they exchange some info, but I
&gt; get an error like &quot;route-client command exited with status 7 \n internal
&gt; error&quot;.
&gt; Where can I find a description of this error?

In general, if the FAQ doesn't cover it, you can search the mailing list 
archives - I like to use
http://www.sandelman.ottawa.on.ca/linux-ipsec/
but you can see doc/mail.html for different archive formats.


Your error comes from the _updown script, which performs some
routing and firewall functions to help Linux FreeS/WAN. More info
is available at doc/firewall.html and man ipsec.conf. Its routing
is integral to the health of Linux FreeS/WAN; it also provides facility
to insert custom firewall rules to be executed when you create or destroy
a connection.

Yours is, of course, a routing error. You can be fairly sure the routing 
machinery is saying &quot;network is unreachable&quot;. There's a FAQ on the 
&quot;network is unreachable&quot; error, but more information is available now; read on.

If your _updown script is recent (for example if it shipped with 
Linux FreeS/WAN 1.91), you will see another debugging line in your logs 
that looks something like this:

&gt; output: /usr/lib/ipsec/_updown: `route add -net 128.174.253.83 
&gt; netmask 255.255.255.255 dev ipsec0 gw 66.92.93.161' failed

This is, of course, the system route command that exited with status 7, 
(ie. failed). Man route for details. Seeing the command typed out yields 
more information. If your _updown script is older, you may wish to update 
it to show the command explicitly.

Three parameters fed to the route command: net, netmask and gw [gateway] 
are derived from things you've put in ipsec.conf.

Net and netmask are derived from the peer's IP and mask. In more detail:

You may see a routing error when routing to a client (ie. subnet), or 
to a host (IPSec gateway or freestanding host; a box that does IPSec for
itself). In _updown, the &quot;route-client&quot; section  is responsible to set up 
the route for IPSec'd (usually, read 'tunneled') packets headed to a 
peer subnet. Similarly, route-host routes IPSec'd packets to a peer host
or IPSec gateway.

When routing to a 'client', net and netmask are ipsec.conf's left- or 
rightsubnet (whichever is not local). Similarly, when routing to a 
'host' the net is left or right. Host netmask is always /32, indicating a 
single machine.

Gw is nexthop's value. Again, the value in question is left- or rightnexthop,
whichever is local. Where left/right or left-/rightnexthop has the special 
value %defaultroute (described in man ipsec.conf), gw will automagically get
the value of the next hop on the default route.

Q: &quot;What's a nexthop and why do I need one?&quot;

A: 'nexthop' is a routing kluge; its value is the next hop away
   from the machine that's doing IPSec, and toward your IPSec peer. 
   You need it to get the processed packets out of the local system and 
   onto the wire. While we often route other packets through the machine 
   that's now doing IPSec, and are done with it, this does not suffice here. 
   After packets are processed with IPSec, this machine needs to know where 
   they go next. Of course using the 'IPSec gateway' as their routing gateway 
   would cause an infinite loop! [To visualize this, see the packet flow 
   diagram at doc/firewall.html.] To avoid this, we route packets through 
   the next hop down their projected path.

Now that you know the background, consider:
1. Did you test routing between the gateways in the absence of Linux
   FreeS/WAN, as recommended? You need to ensure the two machines that
   will be running Linux FreeS/WAN can route to one another before trying to 
   make a secure connection.
2. Is there anything obviously wrong with the sense of your route command?

Normally, this problem is caused by an incorrect local nexthop parameter.
Check out the use of %defaultroute, described in man ipsec.conf. This is
a simple way to set nexthop for most people. To figure nexthop out by hand,
traceroute in-the-clear to your IPSec peer. Nexthop is the traceroute's 
first hop after your IPSec gateway.</PRE>
<H3><A name="unreachable">SIOCADDRT:Network is unreachable</A></H3>
<P>This message is not from FreeS/WAN, but from the Linux IP stack
 itself. That stack is seeing packets it has no route for, either
 because your routing was broken before FreeS/WAN started or because
 FreeS/WAN's changes broke it.</P>
<P>Here is a message from Claudia suggesting ways to diagnose and fix
 such problems:</P>
<PRE>You write,
&gt; I have correctly installed freeswan-1.8 on RH7.0 kernel 2.2.17, but when 
&gt; I setup a VPN connection with the other machine(RH5.2 Kernel 2.0.36 
&gt; freeswan-1.0, it works well.) it told me that 
&gt; &quot;SIOCADDRT:Network is unreachable&quot;!  But the network connection is no 
&gt; problem.

Often this error is the result of a misconfiguration. 

Be sure that you can route successfully in the absence of Linux
FreeS/WAN. (You say this is no problem, so proceed to the next step.)

Use a custom copy of the default updownscript. Do not change the route 
commands, but add a diagnostic message revealing the exact text of the 
route command. Is there a problem with the sense of the route command
that you can see? If so, then re-examine those ipsec.conf settings
that are being sent to the route command. 

You may wish to use the ipsec auto --route and --unroute commands to 
troubleshoot the problem. See man ipsec_auto for details.</PRE>
<P>Since the above message was written, we have modified the updown
 script to provide a better diagnostic for this problem. Check<VAR>
 /var/log/messages</VAR>.</P>
<P>See also the FAQ question<A href="#route-client"> route-client (or
 host) exited with status 7</A>.</P>
<H3><A name="modprobe">ipsec_setup: modprobe: Can't locate module ipsec</A>
</H3>
<H3><A name="noKLIPS">ipsec_setup: Fatal error, kernel appears to lack
 KLIPS</A></H3>
<P>These messages indicate an installation failure. The kernel you are
 running does not contain the<A href="glossary.html#KLIPS"> KLIPS
 (kernel IPsec)</A> code.</P>
<P>Note that the &quot;modprobe: Can't locate module ipsec&quot; message appears
 even if you are not using modules. If there is no KLIPS in your kernel,
 FreeS/WAN tries to load it as a module. If that fails, you get this
 message.</P>
<P>Commands you can quickly try are:</P>
<DL>
<DT><VAR>uname -a</VAR></DT>
<DD>to get details, including compilation date and time, of the
 currently running kernel</DD>
<DT><VAR>ls /</VAR></DT>
<DT><VAR>ls /boot</VAR></DT>
<DD>to ensure a new kernel is where it should be. If kernel compilation
 puts it in<VAR> /</VAR> but<VAR> lilo</VAR> wants it in<VAR> /boot</VAR>
, then you should uncomment the<VAR> INSTALL_PATH=/boot</VAR> line in
 the kernel<VAR> Makefile</VAR>.</DD>
<DT><VAR>more /etc/lilo.conf</VAR></DT>
<DD>to see that<VAR> lilo</VAR> has correct information</DD>
<DT><VAR>lilo</VAR></DT>
<DD>to ensure that information in<VAR> /etc/lilo.conf</VAR> has been
 transferred to the boot sector</DD>
</DL>
<P>If those don't find the problem, you have to go back and check
 through the<A href="install.html"> install</A> procedure to see what
 was missed.</P>
<P>Here is one of Claudia's messages on the topic:</P>
<PRE>&gt; I tried to install freeswan 1.8 on my mandrake 7.2 test box. ...

&gt; It does show version and some output for whack.

Yes, because the Pluto (daemon) part of ipsec is installed correctly, but
as we see below the kernel portion is not.

&gt; However, I get the following from /var/log/messages:
&gt; 
&gt; Mar 11 22:11:55 pavillion ipsec_setup: Starting FreeS/WAN IPsec 1.8...
&gt; Mar 11 22:12:02 pavillion ipsec_setup: modprobe: Can't locate module ipsec
&gt; Mar 11 22:12:02 pavillion ipsec_setup: Fatal error, kernel appears to lack
&gt; KLIPS.

This is your problem. You have not successfully installed a kernel with
IPSec machinery in it. 

Did you build Linux FreeS/WAN as a module? If so, you need to ensure that 
your new module has been installed in the directory where your kernel 
loader normally finds your modules. If not, you need to ensure
that the new IPSec-enabled kernel is being loaded correctly.

See also doc/install.html, and INSTALL in the distro.</PRE>
<H3><A name="noDNS">ipsec_setup: ... failure to fetch key for ... from
 DNS</A></H3>
<P>Quoting Henry:</P>
<PRE>Note that by default, FreeS/WAN is now set up to
     (a) authenticate with RSA keys, and
     (b) fetch the public key of the far end from DNS.
Explicit attention to  ipsec.conf will be needed if you want
to do something different.</PRE>
<P>and Claudia, responding to the same user:</P>
<PRE>You write,

&gt;       My current setup in ipsec.conf is leftrsasigkey=%dns I have 
&gt; commented this and authby=rsasig out. I am able to get ipsec running, 
&gt; but what I find is that the documentation only specifies for %dns are 
&gt; there any other values that can be placed in this variable other than 
&gt; %dns and the key? I am also assuming that this is where I would place 
&gt; my public key for the left and right side as well is this correct?

Valid values for authby= are rsasig and secret, which entail authentication
by RSA signature or by shared secret, respectively. Because you have 
commented authby=rsasig out, you are using the default value of authby=secret. 

When using RSA signatures, there are two ways to get the public key for the
IPSec peer: either copy it directly into *rsasigkey= in ipsec.conf, or
fetch it from dns. The magic value %dns for *rsasigkey parameters says to 
try to fetch the peer's key from dns.

For any parameters, you may find their significance and special values in
man ipsec.conf. If you are setting up keys or secrets, be sure also to
reference man ipsec.secrets.</PRE>
<H3><A name="dup_address">ipsec_setup: ... interfaces ... and ... share
 address ...</A></H3>
<P>This is a fatal error. FreeS/WAN cannot cope with two or more
 interfaces using the same IP address. You must re-configure to avoid
 this.</P>
<P>A mailing list message on the topic from Pluto developer Hugh
 Redelmeier:</P>
<PRE>| I'm trying to get freeswan working between two machine where one has a ppp
| interface.
| I've already suceeded with  two machines with ethernet ports but  the ppp
| interface is causing me problems.
|  basically when I run ipsec start  i get
| ipsec_setup: Starting FreeS/WAN IPsec 1.7...
| ipsec_setup: 003 IP interfaces ppp1 and ppp0 share address 192.168.0.10!
| ipsec_setup: 003 IP interfaces ppp1 and ppp2 share address 192.168.0.10!
| ipsec_setup: 003 IP interfaces ppp0 and ppp2 share address 192.168.0.10!
| ipsec_setup: 003 no public interfaces found
|
| followed by lots of cannot work out interface for connection messages
|
| now I can specify the interface in ipsec.conf to be ppp0 , but this does
| not affect the above behaviour. A quick look in server.c indicates that the
| interfaces value  is not used but some sort of raw detect happens.
|
| I guess I could prevent the formation of the extra ppp interfaces or
| allocate them different ip but I'd  rather not. if at all possible. Any
| suggestions please.

Pluto won't touch an interface that shares an IP address with another.
This will eventually change, but it probably won't happen soon.

For now, you will have to give the ppp1 and ppp2 different addresses.</PRE>
<H3><A name="kflags">ipsec_setup: Cannot adjust kernel flags</A></H3>
<P>A mailing list message form technical lead Henry Spencer:</P>
<PRE>&gt; When FreeS/WAN IPsec 1.7 is starting on my 2.0.38 Linux kernel the following
&gt; error message is generated:
&gt; ipsec_setup: Cannot adjust kernel flags, no /proc/sys/net/ipsec directory!
&gt; What is supposed to create this directory and how can I fix this problem?

I think that directory is a 2.2ism, although I'm not certain (I don't have
a 2.0.xx system handy any more for testing).  Without it, some of the
ipsec.conf config-setup flags won't work, but otherwise things should
function. </PRE>
<P>You also need to enable the<VAR> /proc</VAR> filesystem in your
 kernel configuration for these operations to work.</P>
<H3><A name="message_num">Message numbers (MI3, QR1, et cetera) in Pluto
 messages</A></H3>
<P>Pluto messages often indicate where Pluto is in the IKE protocols.
 The letters indicate<STRONG> M</STRONG>ain mode or<STRONG> Q</STRONG>
uick mode and<STRONG> I</STRONG>nitiator or<STRONG> R</STRONG>esponder.
 The numerals are message sequence numbers. For more detail, see our<A href="ipsec.html#sequence">
 IPsec section</A>.</P>
<H3><A name="conn_name">Connection names in Pluto error messages</A></H3>
<P>From Pluto programmer Hugh Redelmeier:</P>
<PRE>| Jan 17 16:21:10 remus Pluto[13631]: &quot;jumble&quot; #1: responding to Main Mode from Road Warrior 130.205.82.46
| Jan 17 16:21:11 remus Pluto[13631]: &quot;jumble&quot; #1: no suitable connection for peer @banshee.wittsend.com
| 
|     The connection &quot;jumble&quot; has nothing to do with the incoming
| connection requests, which were meant for the connection &quot;banshee&quot;.

You are right.  The message tells you which Connection Pluto is
currently using, which need not be the right one.  It need not be the
right one now for the negotiation to eventually succeed!  This is
described in ipsec_pluto(8) in the section &quot;Road Warrior Support&quot;.

There are two times when Pluto will consider switching Connections for
a state object.  Both are in response to receiving ID payloads (one in
Phase 1 / Main Mode and one in Phase 2 / Quick Mode).  The second is
not unique to Road Warriors.  In fact, neither is the first any more
(two connections for the same pair of hosts could differ in Phase 1 ID
payload; probably nobody else has tried this).</PRE>
<H3><A name="cantorient">Pluto: ... can't orient connection</A></H3>
<P>Older versions of FreeS/WAN used this message. The same error now
 gives the &quot;we have no ipsecN ...&quot; error described just below.</P>
<H3><A name="no.interface">... we have no ipsecN interface for either
 end of this connection</A></H3>
<P>Your tunnel has no IP address which matches the IP address of any of
 the available IPsec interfaces. Either you've misconfigured the
 connection, or you need to define an appropriate IPsec interface
 connection.<VAR> interfaces=%defaultroute</VAR> works in many cases.</P>
<P>A longer story: Pluto needs to know whether it is running on the
 machine which the connection description calls<VAR> left</VAR> or on<VAR>
 right</VAR>. It figures that out by:</P>
<UL>
<LI>looking at the interfaces given in<VAR> interfaces=</VAR> lines in
 the<VAR> config setup</VAR> section</LI>
<LI>discovering the IP addresses for those interfaces</LI>
<LI>searching for a match between those addresses and the ones given in<VAR>
 left=</VAR> or<VAR> right=</VAR> lines.</LI>
</UL>
<P>Normally a match is found. Then Pluto knows where it is and can set
 up other things (for example, if it is<VAR> left</VAR>) using
 parameters such as<VAR> leftsubnet</VAR> and<VAR> leftnexthop</VAR>,
 and sending its outgoing packets to<VAR> right</VAR>.</P>
<P>If no match is found, it emits the above error message.</P>
<H3><A name="noconn">Pluto: ... no connection is known</A></H3>
<P>This error message occurs when a remote system attempts to negotiate
 a connection and Pluto does not have a connection description that
 matches what the remote system has requested. The most common cause is
 a configuration error on one end or the other.</P>
<P>Parameters involved in this match are<VAR> left</VAR>,<VAR> right</VAR>
,<VAR> leftsubnet</VAR> and<VAR> rightsubnet</VAR>.</P>
<P><STRONG>The match must be exact</STRONG>. For example, if your left
 subnet is a.b.c.0/24 then neither a single machine in that net nor a
 smaller subnet such as a.b.c.64/26 will be considered a match.</P>
<P>The message can also occur when an appropriate description exists but
 Pluto has not loaded it. Use an<VAR> auto=add</VAR> statement in the
 connection description, or an<VAR> ipsec auto --add &lt;conn_name&gt;</VAR>
 command, to correct this.</P>
<P>An explanation from the Pluto developer:</P>
<PRE>| Jul 12 15:00:22 sohar58 Pluto[574]: &quot;corp_road&quot; #2: cannot respond to IPsec
| SA request because no connection is known for
| 216.112.83.112/32===216.112.83.112...216.67.25.118

This is the first message from the Pluto log showing a problem.  It
means that PGPnet is trying to negotiate a set of SAs with this
topology:

216.112.83.112/32===216.112.83.112...216.67.25.118
^^^^^^^^^^^^^^^^^   ^^^^^^^^^^^^^^   ^^^^^^^^^^^^^
client on our side  our host         PGPnet host, no client

None of the conns you showed look like this.

Use
        ipsec auto --status
to see a snapshot of what connections are in pluto, what
negotiations are going on, and what SAs are established.

The leftsubnet= (client) in your conn is 216.112.83.64/26.  It must
exactly match what pluto is looking for, and it does not.</PRE>
<H3><A name="nosuit">Pluto: ... no suitable connection ...</A></H3>
<P>This is similar to the<A href="#noconn"> no connection known</A>
 error, but occurs at a different point in Pluto processing.</P>
<P>Here is one of Claudia's messages explaining the problem:</P>
<PRE>You write,

&gt; What could be the reason of the following error? 
&gt; &quot;no suitable connection for peer '@xforce'&quot;

When a connection is initiated by the peer, Pluto must choose which entry in 
the conf file best matches the incoming connection. A preliminary choice is 
made on the basis of source and destination IPs, since that information is 
available at that time. 

A payload containing an ID arrives later in the negotiation. Based on this
id and the *id= parameters, Pluto refines its conn selection. ...

The message &quot;no suitable connection&quot; indicates that in this refining step,
Pluto does not find a connection that matches that ID.

Please see &quot;Selecting a connection when responding&quot; in man ipsec_pluto for
more details.</PRE>
<P>See also<A href="#conn_name"> Connection names in Pluto error
 messages</A>.</P>
<H3><A name="noconn.auth">Pluto: ... no connection has been authorized</A>
</H3>
<P>Here is one of Claudia's messages discussing this problem:</P>
<PRE>You write,

&gt;  May 22 10:46:31 debian Pluto[25834]: packet from x.y.z.p:10014: 
&gt;  initial Main Mode message from x.y.z.p:10014 
                            but no connection has been authorized

This error occurs early in the connection negotiation process,
at the first step of IKE negotiation (Main Mode), which is itself the 
first of two negotiation phases involved in creating an IPSec connection.

Here, Linux FreeS/WAN receives a packet from a potential peer, which 
requests that they begin discussing a connection.

The &quot;no connection has been authorized&quot; means that there is no connection 
description in Linux FreeS/WAN's internal database that can be used to 
link your ipsec interface with that peer.

&quot;But of course I configured that connection!&quot; 

It may be that the appropriate connection description exists in ipsec.conf 
but has not been added to the database with ipsec auto --add myconn or the 
auto=add method. Or, the connection description may be misconfigured.

The only parameters that are relevant in this decision are left= and right= .
Local and remote ports are also taken into account -- we see that the port 
is printed in the message above -- but there is no way to control these
in ipsec.conf.


Failure at &quot;no connection has been authorized&quot; is similar to the
&quot;no connection is known for...&quot; error in the FAQ, and the &quot;no suitable
connection&quot; error described in the snapshot's FAQ. In all three cases,
Linux FreeS/WAN is trying to match parameters received in the
negotiation with the connection description in the local config file.

As it receives more information, its matches take more parameters into 
account, and become more precise:  first the pair of potential peers,
then the peer IDs, then the endpoints (including any subnets).

The &quot;no suitable connection for peer *&quot; occurs toward the end of IKE 
(Main Mode) negotiation, when the IDs are matched.

&quot;no connection is known for a/b===c...d&quot; is seen at the beginning of IPSec 
(Quick Mode, phase 2) negotiation, when the connections are matched using
left, right, and any information about the subnets.</PRE>
<H3><A name="noDESsupport">Pluto: ... OAKLEY_DES_CBC is not supported.</A>
</H3>
<P>This message occurs when the other system attempts to negotiate a
 connection using<A href="glossary.html#DES"> single DES</A>, which we
 do not support because it is<A href="politics.html#desnotsecure">
 insecure</A>.</P>
<P>Our interoperation document has suggestions for<A href="interop.html#noDES">
 how to deal with</A> systems that attempt to use single DES.</P>
<H3><A name="notransform">Pluto: ... no acceptable transform</A></H3>
<P>This message means that the other gateway has made a proposal for
 connection parameters, but nothing they proposed is acceptable to
 Pluto. Possible causes include:</P>
<UL>
<LI>misconfiguration on either end</LI>
<LI>policy incompatibilities, for example we require encrypted
 connections but they are trying to create one with just authentication</LI>
<LI>interoperation problems, for example they offer only single DES and
 FreeS/WAN does not support that. See<A href="interop.html#interop.problem">
 discussion</A> in our interoperation document.</LI>
</UL>
<P>A more detailed explanation, from Pluto programmer Hugh Redelmeier:</P>
<PRE>Background:

When one IKE system (for example, Pluto) is negotiating with another
to create an SA, the Initiator proposes a bunch of choices and the
Responder replies with one that it has selected.

The structure of the choices is fairly complicated.  An SA payload
contains a list of lists of &quot;Proposals&quot;.  The outer list is a set of
choices: the selection must be from one element of this list.

Each of these elements is a list of Proposals.  A selection must be
made from each of the elements of the inner list.  In other words,
*all* of them apply (that is how, for example, both AH and ESP can
apply at once).

Within each of these Proposals is a list of Transforms.  For each
Proposal selected, one Transform must be selected (in other words,
each Proposal provides a choice of Transforms).

Each Transform is made up of a list of Attributes describing, well,
attributes.  Such as lifetime of the SA.  Such as algorithm to be
used.  All the Attributes apply to a Transform.

You will have noticed a pattern here: layers alternate between being
disjunctions (&quot;or&quot;) and conjunctions (&quot;and&quot;).

For Phase 1 / Main Mode (negotiating an ISAKMP SA), this structure is
cut back.  There must be exactly one Proposal.  So this degenerates to
a list of Transforms, one of which must be chosen.

In your case, no proposal was considered acceptable to Pluto (the
Responder).  So negotiation ceased.  Pluto logs the reason it rejects
each Transform.  So look back in the log to see what is going wrong.</PRE>
<H3><A name="rsasigkey">rsasigkey dumps core</A></H3>
 A comment on this error from Henry:
<PRE>On Fri, 29 Jun 2001, Rodrigo Gruppelli wrote:
&gt; ...Well, it seem that there's
&gt; another problem with it. When I try to generate a pair of RSA keys,
&gt; rsasigkey cores dump...

*That* is a neon sign flashing &quot;GMP LIBRARY IS BROKEN&quot;.  Rsasigkey calls
GMP a lot, and our own library a little bit, and that's very nearly all it
does.  Barring bugs in its code or our library -- which have happened, but
not very often -- a problem in rsasigkey is a problem in GMP.</PRE>
<P>See the next question for how to deal with GMP errors.</P>
<H3><A name="sig4">!Pluto failure!: ... exited with ... signal 4</A></H3>
<P>Pluto has died. Signal 4 is SIGILL, illegal instruction.</P>
<P>The most likely cause is that your<A href="glossary.html#GMP"> GMP</A>
 (GNU multi-precision) library is compiled for a different processor
 than what you are running on. Pluto uses that library for its public
 key calculations.</P>
<P>Try getting the GMP sources and recompile for your processor type.
 Most Linux distributions will include this source, or you can download
 it from the<A href="http://www.swox.com/gmp/"> GMP home page</A>.</P>
<H3><A name="econnrefused">ECONNREFUSED error message</A></H3>
<P>From John Denker, on the mailing list:</P>
<PRE>1)  The log message
  some IKE message we sent has been rejected with 
  ECONNREFUSED (kernel supplied no details)
is much more suitable than the previous version.  Thanks.

2) Minor suggestion for further improvement: it might be worth mentioning
that the command
  tcpdump -i eth1 icmp[0] != 8 and icmp[0] != 0
is useful for tracking down the details in question.  We shouldn't expect
all IPsec users to figure that out on their own.  The log message might
even provide a hint as to where to look in the docs.</PRE>
<P>Reply From Pluto developer Hugh Redelmeier</P>
<PRE>Good idea.

I've added a bit pluto(8)'s BUGS section along these lines.
I didn't have the heart to lengthen this message.</PRE>
<H3><A name="no_eroute">klips_debug: ... no eroute!</A></H3>
<P>This message means<A href="glossary.html#KLIPS"> KLIPS</A> has
 received a packet for which no IPsec tunnel has been defined.</P>
<P>Here is a more detailed duscussion from the team's tech support
 person Claudia Schmeing, responding to a query on the mailing list:</P>
<PRE>&gt; Why ipsec reports no eroute! ???? IP Masq... is disabled.

In general, more information is required so that people on the list may
give you informed input. See doc/prob.report.</PRE>
<P>The document she refers to has since been replaced by a<A href="trouble.html#prob.report">
 section</A> of the troubleshooting document.</P>
<PRE>However, I can make some general comments on this type of error.

This error usually looks something like this (clipped from an archived
message):

&gt; ttl:64 proto:1 chk:45459 saddr:192.168.1.2 daddr:192.168.100.1
&gt; ... klips_debug:ipsec_findroute: 192.168.1.2-&gt;192.168.100.1
&gt; ... klips_debug:rj_match: * See if we match exactly as a host destination
&gt; ... klips_debug:rj_match: ** try to match a leaf, t=0xc1a260b0
&gt; ... klips_debug:rj_match: *** start searching up the tree, t=0xc1a260b0
&gt; ... klips_debug:rj_match: **** t=0xc1a260c8
&gt; ... klips_debug:rj_match: **** t=0xc1fe5960
&gt; ... klips_debug:rj_match: ***** not found.
&gt; ... klips_debug:ipsec_tunnel_start_xmit: Original head/tailroom: 2, 28
&gt; ... klips_debug:ipsec_tunnel_start_xmit: no eroute!: ts=47.3030, dropping.


What does this mean?
- --------------------

&quot;eroute&quot; stands for &quot;extended route&quot;, and is a special type of route 
internal to Linux FreeS/WAN. For more information about this type of route, 
see the section of man ipsec_auto on ipsec auto --route.

&quot;no eroute!&quot; here means, roughly, that Linux FreeS/WAN cannot find an 
appropriate tunnel that should have delivered this packet. Linux 
FreeS/WAN therefore drops the packet, with the message &quot;no eroute! ...
dropping&quot;, on the assumption that this packet is not a legitimate 
transmission through a properly constructed tunnel.


How does this situation come about?
- -----------------------------------

Linux FreeS/WAN has a number of connection descriptions defined in 
ipsec.conf. These must be successfully brought &quot;up&quot; to form actual tunnels.
(see doc/setup.html's step 15, man ipsec.conf and man ipsec_auto 
for details).

Such connections are often specific to the endpoints' IPs. However, in 
some cases they may be more general, for example in the case of 
Road Warriors where left or right is the special value %any.

When Linux FreeS/WAN receives a packet, it verifies that the packet has
come through a legitimate channel, by checking that there is an
appropriate tunnel through which this packet might legitimately have
arrived. This is the process we see above.

First, it checks for an eroute that exactly matches the packet. In the 
example above, we see it checking for a route that begins at 192.168.1.2
and ends at 192.168.100.1. This search favours the most specific match that
would apply to the route between these IPs. So, if there is a connection 
description exactly matching these IPs, the search will end there. If not, 
the code will search for a more general description matching the IPs.
If there is no match, either specific or general, the packet will be
dropped, as we see, above.

Unless you are working with Road Warriors, only the first, specific part 
of the matching process is likely to be relevant to you.


&quot;But I defined the tunnel, and it came up, why do I have this error?&quot;
- ---------------------------------------------------------------------

One of the most common causes of this error is failure to specify enough
connection descriptions to cover all needed tunnels between any two 
gateways and their respective subnets. As you have noticed, troubleshooting
this error may be complicated by the use of IP Masq. However, this error is
not limited to cases where IP Masq is used. 

See doc/configuration.html#multitunnel for a detailed example of the 
solution to this type of problem.</PRE>
<P>The documentation section she refers to is now<A href="adv_config.html#multitunnel">
 here</A>.</P>
<H3><A name="SAused">... trouble writing to /dev/ipsec ... SA already in
 use</A></H3>
<P>This error message occurs when two manual connections are set up with
 the same SPI value.</P>
<P>See the FAQ for<A href="#spi_error"> One manual connection works, but
 second one fails</A>.</P>
<H3><A name="ignore">... ignoring ... payload</A></H3>
<P>This message is harmless. The IKE protocol provides for a number of
 optional messages types:</P>
<UL>
<LI>delete SA</LI>
<LI>initial contact</LI>
<LI>vendor ID</LI>
<LI>...</LI>
</UL>
<P>An implementation is never required to send these, but they are
 allowed to. The receiver is not required to do anything with them.
 FreeS/WAN ignores them, but notifies you via the logs.</P>
<P>For the &quot;ignoring delete SA Payload&quot; message, see also our discussion
 of cleaning up<A href="#deadtunnel"> dead tunnels</A>.</P>
<H3><A name="unknown_rightcert">unknown parameter name &quot;rightcert&quot;</A></H3>
<P>This message can appear when you've upgraded an X.509-enabled Linux
 FreeS/WAN with a vanilla Linux FreeS/WAN. To use your X.509 configs you
 will need to overwrite the new install with<A HREF="http://www.freeswan.ca">
 Super FreeS/WAN</A>, or add the<A HREF="http://www.strongsec.ca/freeswan">
 X.509 patch</A> by hand.</P>
<H2><A name="spam">Why don't you restrict the mailing lists to reduce
 spam?</A></H2>
<P>As a matter of policy, some of our<A href="mail.html"> mailing lists</A>
 need to be open to non-subscribers. Project management feel strongly
 that maintaining this openness is more important than blocking spam.</P>
<UL>
<LI>Users should be able to get help or report bugs without subscribing.</LI>
<LI>Even a user who is subscribed may not have access to his or her
 subscribed account when he or she needs help, miles from home base in
 the middle of setting up a client's gateway.</LI>
<LI>There is arguably a legal requirement for this policy. A US resident
 or citizen could be charged under munitions export laws for providing
 technical assistance to a foreign cryptographic project. Such a charge
 would be more easily defended if the discussion takes place in public,
 on an open list.</LI>
</UL>
<P>This has been discussed several times at some length on the list. See
 the<A href="mail.html#archive"> list archives</A>. Bringing the topic
 up again is unlikely to be useful. Please don't. Or at the very least,
 please don't without reading the archives and being certain that
 whatever you are about to suggest has not yet been discussed.</P>
<P>Project technical lead Henry Spencer summarised one discussion:</P>
<BLOCKQUOTE> For the third and last time: this list *will* *not* do
 address-based filtering. This is a policy decision, not an
 implementation problem. The decision is final, and is not open to
 discussion. This needs to be communicated better to people, and steps
 are being taken to do that.</BLOCKQUOTE>
<P>Adding this FAQ section is one of the steps he refers to.</P>
<P>You have various options other than just putting up with the spam,
 filtering it yourself, or unsubscribing:</P>
<UL>
<LI>subscribe only to one or both of our lists with restricted posting
 rules:
<UL>
<LI><A href="mailto:briefs@lists.freeswan.org?body=subscribe">briefs</A>
, weekly list summaries</LI>
<LI><A href="mailto:announce@lists.freeswan.org?body=subscribe">announce</A>
, project-related announcements</LI>
</UL>
</LI>
<LI>read the other lists via the<A href="mail.html#archive"> archives</A>
</LI>
</UL>
<P>A number of tools are available to filter mail.</P>
<UL>
<LI>Many mail readers include some filtering capability.</LI>
<LI>Many Linux distributions include<A href="http://www.procmail.org/">
 procmail(8)</A> for server-side filtering.</LI>
<LI>The<A href="http://www.spambouncer.org/"> Spam Bouncer</A> is a set
 of procmail(8) filters designed to combat spam.</LI>
<LI>Roaring Penguin have a<A href="http://www.roaringpenguin.com/mimedefang/">
 MIME defanger</A> that removes potentially dangerous attachments.</LI>
</UL>
<P>If you use your ISP's mail server rather than running your own,
 consider suggesting to the ISP that they tag suspected spam as<A href="http://www.msen.com/1997/spam.html#SUSPECTED">
 this ISP</A> does. They could just refuse mail from dubious sources,
 but that is tricky and runs some risk of losing valuable mail or
 senselessly annoying senders and their admins. However, they can safely
 tag and deliver dubious mail. The tags can greatly assist your
 filtering.</P>
<P>For information on tracking down spammers, see these<A href="http://www.rahul.net/falk/#howtos">
 HowTos</A>, or the<A href="http://www.sputum.com/index2.html"> Sputum</A>
 site. Sputum have a Linux anti-spam screensaver available for download.</P>
<P>Here is a more detailed message from Henry:</P>
<PRE>On Mon, 15 Jan 2001, Jay Vaughan wrote:
&gt; I know I'm flogging a dead horse here, but I'm curious as to the reasons for
&gt; an aversion for a subscriber-only mailing list?

Once again:  for legal reasons, it is important that discussions of these
things be held in a public place -- the list -- and we do not want to
force people to subscribe to the list just to ask one question, because
that may be more than merely inconvenient for them.  There are also real
difficulties with people who are temporarily forced to use alternate
addresses; that is precisely the time when they may be most in need of
help, yet a subscribers-only policy shuts them out.

These issues do not apply to most mailing lists, but for a list that is
(necessarily) the primary user support route for a crypto package, they
are very important.  This is *not* an ordinary mailing list; it has to
function under awkward constraints that make various simplistic solutions
inapplicable or undesirable. 

&gt; We're *ALL* sick of hearing about list management problems, not just you
&gt; old-timers, so why don't you DO SOMETHING EFFECTIVE ABOUT IT...

Because it's a lot harder than it looks, and many existing &quot;solutions&quot;
have problems when examined closely.

&gt; A suggestion for you, based on 10 years of experience with management of my
&gt; own mailing lists would be to use mailman, which includes pretty much every
&gt; feature under the sun that you guys need and want, plus some.  The URL for
&gt; mailman...

I assure you, we're aware of mailman.  Along with a whole bunch of others,
including some you almost certainly have never heard of (I hadn't!).

&gt; As for the argument that the list shouldn't be configured to enforce
&gt; subscription - I contend that it *SHOULD* AT LEAST require manual address
&gt; verification in order for posts to be redirected.

You do realize, I hope, that interposing such a manual step might cause
your government to decide that this is not truly a public forum, and thus
you could go to jail if you don't get approval from them before mailing to
it?  If you think this sounds irrational, your government is noted for
making irrational decisions in this area; we can't assume that they will
suddenly start being sensible.  See above about awkward constraints.  You
may be willing to take the risk, but we can't, in good conscience, insist
that all users with problems do so. 

                                                          Henry Spencer
                                                       henry@spsystems.net</PRE>
<P>and a message on the topic from project leader John Gilmore:</P>
<PRE>Subject: Re: The linux-ipsec list's topic
   Date: Sat, 30 Dec 2000
   From: John Gilmore &lt;gnu@toad.com&gt;

I'll post this single message, once only, in this discussion, and then
not burden the list with any further off-topic messages.  I encourage
everyone on the list to restrain themself from posting ANY off-topic
messages to the linux-ipsec list.

The topic of the linux-ipsec mailing list is the FreeS/WAN software.

I frequently see &quot;discussions about spam on a list&quot; overwhelm the
volume of &quot;actual spam&quot; on a list. BOTH kinds of messages are
off-topic messages.  Twenty anti-spam messages take just as long to
detect and discard as twenty spam messages.

The Linux-ipsec list encourages on-topic messages from people who have
not joined the list itself.  We will not censor messages to the list
based on where they originate, or what return address they contain.
In other words, non-subscribers ARE allowed to post, and this will not
change.  My own valid contributions have been rejected out-of-hand by
too many other mailing lists for me to want to impose that censorship
on anybody else's contributions.  And every day I see the damage that
anti-spam zeal is causing in many other ways; that zeal is far more
damaging to the culture of the Internet than the nuisance of spam.

In general, it is the responsibility of recipients to filter,
prioritize, or otherwise manage the handling of email that comes to
them.  It is not the responsibility of the rest of the Internet
community to refrain from sending messages to recipients that they
might not want to see.  If your software infrastructure for managing
your incoming email is insufficient, then improve it.  If you think
the signal-to-noise ratio on linux-ipsec is too poor, then please
unsubscribe.  But don't further increase the noise by posting to the
linux-ipsec list about those topics.

        John Gilmore
        founder &amp; sponsor, FreeS/WAN project</PRE>
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